Log Message:
Update capistrano to 2.15.5.

## 2.15.5 / July 4 2013

* Fix multistage argument parsing when using the `-s` option. (@jmazzi)
* Tweaks to the asset recipes. (@curtislinden)
* Use quotes around SCM usernames and passwords (@carloslopes)
* Avoid git warning when cloning Git repository using sha1 (@bpaquet)

## 2.15.4 / April 29 2013

* Fix parallel command logging (@gnufied)
* Fix a double-asset manifest problem on Rails upgrades. (@jimryan)

## 2.15.3 / April 25 2012

* For deploy:cleanup, use try_sudo with rm command. (@joshstaiger)
* Restore maintenance.rhtml (@chulkilee)
* Fixes GH-434, If branches is an array of array, iterate them separately. (@gnufied)

A big "thank you" to the people who've pushed really amazing patches to the
2.15.x branch so soon after it's release. 2.15.0 was just too huge to go out
bug free.

## 2.15.2 / April 24 2013

* Fixed a bug with asset_paths (String vs. Array). (@joeycarmello)

## 2.15.1 / April 23 2013

* Support for Rails 4 (and other) randomised asset manifest names. (@jimryan)

## 2.15.0 / April 23 2013

* New varaible :shared_assets_prefix to allow people to host somewhere other
  than `/assets/`. Default is `assets`.
* Bring back web:enable and web:disable tasks. Sincerely apologies to all affected
  removing these was one of the most glaring mistakes we've made on this project
  and I feel personally responsible.
* Makes :git_shallow_clone work with branches (@cannikin)
* Avoid removing required assets (@bosko)
* Fix escaping of asset_paths when calling `deploy:finalize_update` (@mcary)
* Improve parallel command logging (@mpapis)
* Allow updating variables in the cap shell `cap> set :some_setting new_value`
  (@jpfuentes2)
* Add the option to configure `Capistrano::Logger.default_formatters=` this
  relates to the previous merging of the capistrano-colors gem. (@kellyredding)
* Don't attempt to connect to a nil `:gateway` (@mattheath)
* Simplify our .gemspec dependency list (@timoschilling)
* Make the existece of `config/deploy/{stage}.rb` optional, it'll be loaded if
  it exists, otherwise we continue without it (@ymainier)
* Misc spelling/typo fixes. (@mv)
* Update mtime and atime with touch when fixing asset timestamps (@wildoats)
* Change call of `rake {env} precompile:all` to drop the errornous `{env}` (@zxiest)
* Evaluate assets_role at runtime using a lambda (@nlenepveu)
* Handle when hosts (for example by joining/leaving the no_release meta group)
  have different old releases for `deploy:cleanup` (@oggy)
* Check for nil when tearing down connections (@yyuu)
* Go back to using SCP for uploads as against SFTP (@pjungwir)
* Added an option to dereference symlinks when using the :copy strategy
  (`set :copy_dereference_symlink, true`) useful when your working directory
  contains files symlinked in from outside your project root (@mehmetc)
* Small typo fix in README (@yule)
* Add Ruby 2.0.0-p0 to the TravisCI build (@jarrettmeyer)
* Add the option to set the shared asset prefix for Rails,
  (`set :shared_assets_prefix, "my_shared_assets"`) corresponds with it's
  namesake in Rails. By default is set to `assets`. (@spectator)
* Improved error messages for `cap {stage} deploy:check` (@petems)
* Make `run_locally` work with the `--dry-run` flag. (@flagthisiskun)
* Fix a link in the README to writing a good commit message. (@mhutchin)
* Code style fixes (@mv)
* Report differently if the command was killed by a signal (for example the
  oom killer on Ubuntu/Debian). (@tanob)