Log Message:
Update to 0.64
Update DEPENDS

Upstream changes:
0.64: # 2013-06-02T09:44:59+0200
- The build directory is removed before a new build.
- New command: `install-multiple`
- `clean` command now also removes tarballs
- `install` command has many extra convienent flags.
- Use "http://www.cpan.org" as the default CPAN mirror instead of \ 
"http://search.cpan.org/CPAN"
- Remove the --insecure/--no-check-certificate command bflags when invoking \ 
curl/wget.

0.63: # 2013-05-06T16:53:48+0200
- Remove `install-ack` command.
  - Due to the new architecture of ack2, it does not make sense
    to install the standalone executable anymore. Thus it's better not
    to do the installation with perlbrew.
- Fix the `use` and `switch` command when switching between binary incompatible \ 
perl installations. See GH #297

0.62: # 2013-04-07T17:43:58+0800
- Fix `list-modules` under lib env. It lists all modules in the lib, and in the base.
- Use the original grep command to prevent aliases from breaking the content of \ 
init. GH #307
- `perlbrew alias help` is now the same as `perlbrew help alias`
- `perlbrew exec --with ...` now preserve the order of specified names.

0.61:
- Fix bashrc on various OS/shell. See GH #302

0.60: # 2013-03-17T21:44:12+0100
- Exit status handling in bash function. See \ 
ed29288ab50a15d7df86d69cfcbddf108674eb07 for more details.
- Fix compatibility with recent local::lib version.
- Delay the loading of server modules.
- Fix warnings when runing `perlbrew off`

0.59: # 2013-02-17T12:34:10+0100
- New feature: "perlbrew install --switch $perl"
- New feature: "perlbrew install stable"
- Fix "--quiet" options for "exec" command
- Fix mulitple test failures and warnings

0.58: # 2012-11-16T08:45:18+0100
- Fix infinite re-exec loop as identified in #263
- Fix a case where PERL5LIB still contains previous entries after deactivating \ 
or activating other ones.

0.57: # 2012-11-13T19:57:03+0100
- Fix an infinite re-exec loop

0.56: # 2012-11-11T23:10:30+0100
- Fix GH #261, which breaks `off` and `swich-off` commands.

0.55:
- Revert the requirement of 5.8.8. Now require 5.8
- Add PERLBREW_CPAN_MIRROR environment variable
- Deal with a minor local::lib path problem. See GH #254.