Prevent making useless symbols.

Groups are concatenated with ':' in Bundler::Settings#without=,
and splited by ':' in Bundler::Settings#without. So replace ' '
with ':' to prevent making useless symbols and other objects.
Show that current_release can be overridden.
Sort `bundle outdated` output (as `bundle show`) ; add tests.
Ruby 1.8.7 does not have lookbehind ; fix the regex.
Adds bundle licenses cli task
Typo
Add :gist option for gems embedded in gists
Fix typos in error messages
Allow optional gem push via gem_push environment variable.
Oops. That should be $/, which is "\n" on UNIX systems and "\r\n" on Windows.
Add the .txt extension to the LICENSE file.
Check that LICENSE.txt was created.
Merge pull request #2001 from postmodern/txt

LICENSE.txt
Merge pull request #1998 from postmodern/patch-1

Fixed typo. $/ and NOT $\
Issue #2000 Add test for conflict markers in Gemfile.lock
Raise error if Gemfile.lock contains conflict markers, closes #2000
Check for nil PATH

fixes #2006
Issue #2000 improve error message
loosen ruby directive for engines

allow other engines to qualify when the engine is omitted. So, in the
Gemfile:

ruby "1.9.3"

will work with JRuby and RBX as long as the RUBY_VERSION matches
Don't actually care if git repo is inside the repository, always cache it, closes #1989