Log Message:
Update ruby-bundler to 1.7.3, including security fix for CVE-2013-0334.

## 1.7.3 (2014-09-14)

Bugfixes:

  - `extconf.rb` is now generated with the right path for `create_makefile` \ 
(@andremedeiros)
  - Fix various Ruby warnings (@piotrsanarki, @indirect)

## 1.7.2 (2014-08-23)

Bugfixes:

  - Revert gem source sorting in lock files (@indirect)

## 1.7.1 (2014-08-20)

Bugfixes:

  - Install gems from one source needed by gems in another source (@indirect)
  - Install the same gem versions even after some are installed (@tmoore)
  - Download specs only when installing from servers (@indirect)

## 1.7.0 (2014-08-13)

Security:

  - Fix for CVE-2013-0334, installing gems from an unexpected source (@tmoore)

Features:

  - Gemfile `source` calls now take a block containing gems from that source \ 
(@tmoore)
  - added the `:source` option to `gem` to specify a source (@tmoore)

Bugfixes:

  - warn on ambiguous gems available from more than one source (@tmoore)

## 1.6.5 (2014-07-23)

Bugfixes:

  - require openssl explicitly to fix rare HTTPS request failures (@indirect, #3107)

## 1.6.4 (2014-07-17)

Bugfixes:

  - fix undefined constant error when can't find gem during binstubs (#3095, \ 
@jetaggart)
  - work when installed git gems are not writable (#3092, @pmahoney)
  - don't store configured source credentials in Gemfile.lock (#3045, @lhz)
  - don't include config source credentials in the lockfile (Lars Haugseth)
  - use threads for jobs on Rubinius (@YorickPeterse)
  - skip dependencies from other platforms (@mvz)
  - work when Rubygems was built without SSL (@andremedeiros)

## 1.6.3 (2014-06-16)

Bugfixes:

  - fix regression when resolving many conflicts (#2994, @Who828)
  - use local gemspec for builtin gems during install --local (#3041, @Who828)
  - don't warn about sudo when installing on Windows (#2984, @indirect)
  - shell escape `bundle open` arguments (@indirect)

## 1.6.2 (2014-04-13)

Bugfixes:

  - fix an exception when using builtin gems (#2915, #2963, @gnufied)
  - cache gems that are built in to the running ruby (#2975, @indirect)
  - re-allow deploying cached git gems without git installed (#2968, @aughr)
  - keep standalone working even with builtin gems (@indirect)
  - don't update vendor/cache in deployment mode (#2921, @indirect)

Features:

  - warn informatively when `bundle install` is run as root (#2936, @1337807)

## 1.6.1 (2014-04-02)

Bugfixes:

  - update C extensions when git gem versions change (#2948, @dylanahsmith)

Features:

  - add support for C extensions in sudo mode on Rubygems 2.2

## 1.6.0 (2014-03-28)

Bugfixes:

  - many Gemfiles that caused incorrect errors now resolve correctly (@Who828)
  - redirects across hosts now work on rubies without OpenSSL (#2686, @grddev)
  - gemspecs now handle filenames with newlines (#2634, @jasonmp85)
  - support escaped characters in usernames and passwords (@punkie)
  - no more exception on `update GEM` without lock file (@simi)
  - allow long config values (#2823, @kgrz)
  - cache successfully even locked to gems shipped with Ruby (#2869, @aughr)
  - respect NO_PROXY even if a proxy is configured (#2878, @stlay)
  - only retry git commands that hit the network (#2899, @timmoore)
  - fix NameError regression when OpenSSL is not available (#2898, @timmoore)
  - handle exception installing when build_info owned by root (@Who828)
  - skip HTTP redirects from rubygems.org, huge speed boost (@Who828)

Features:

  - resolver rewritten to avoid recursion (@Who828)
  - add `git_source` for custom options like :github and :gist (@strzalek)
  - HTTP auth may now be stored in `bundle config` (@smashwilson)
  - some complex Gemfiles are resolved up to 10x faster (@Who828)
  - add support for IRB alternatives such as Pry and Ripl (@joallard, @postmodern)
  - highlight installed or updated gems (#2722, #2741, @yaotti, @simi)
  - display the `post_install_message` for gems installed via :git (@phallstrom)
  - `bundle outdated --strict` now only reports allowed updates (@davidblondeau)
  - `bundle show --verbose` Add gem summary to the output (@lardcanoe)
  - `bundle gem GEM --ext` now generates a skeleton for a C extension (@superdealloc)
  - Avoid using threequals operator where possible (@as-cii)

Documentation:

  - Add missing switches for bundle-install(1) and bundle-update(1) (@as-cii)