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.
set $MANPATH in Bundler::Runtime#setup_environment

This lets `bundle exec man ...` show man pages from bundled gems.
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Sort `bundle outdated` output (as `bundle show`) ; add tests.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
do not explode if branch is not given for local git repos
Add :gist option for gems embedded in gists
Fix typos in error messages
Always try to keep original GEM_PATH

This fixes a problem which occures when you want to run `bundle` command
inside code that already loads `Gemfile`. When you start a command with
`bundle exec` it sets `RUBYOPT` to
`-I$PATH_TO_BUNDLER -r"bundler/setup"`. Because of that, when you run
the actual command it already requires bundler, which is fine, but since
`GEM_PATH` was cleared on the first run `ORIGINAL_ENV` will include
empty `GEM_PATH`. Now when you run `Bundler.with_clean_env`, you will
not have any bundler specific env variables, but you will also not have
original gem path, which will make it impossible to run any gem.

To fix this I try to always keep a reference to original gem path, so
it's not emptied along the way.
Merge pull request #1920 from drogus/gem_path_fix

Always try to keep original GEM_PATH
Rakefiles aren't really supposed to be executable
require 'newgem/version'

because require hashes based on the string, not the expanded path of 
the file, it's important that we require the version file the same 
way that it will be required elsewhere to avoid constant warnings.
handle syntax errors in Ruby gemspecs

fixes #1974
Describe how to check for problematic gems
Allowing git local override to to accept :branch, :tag or :ref
remove all requirements for local override.
Merge pull request #1980 from phil-monroe/master

Remove all requirements from local override
Merge remote-tracking branch 'rkh/optional-branch'

Conflicts:
	lib/bundler/source.rb
	spec/install/git_spec.rb