Use ThreadWorker on Rubinius.

Rubinius doesn't have a GIL and has proper support for threading. As such
Bundler can use the ThreadWorker class instead of the UnixWorker class.
make bundler as fast as bundle
Don't include configured source credentials in lockfile.

Conflicts:
	CHANGELOG.md
Stop @parndt from getting so many contributions in his graph.

The lovely and brilliant @parndt goes around sending PR's to enable
syntax highlighting for this line of the README.  I'm heading him off at
the pass. :heart:
depend on rake 10.x, semantically

makes rubygems happy
Skip non-local dependencies more rigourously
move the dev deps list into the gemspec
depend on rspec 3 now the codebase is updated
Slashify .gitignore template.

Without the initial `/` all such matches within the repo get ignored,
and without the trailing slash files as well as directories of that
name get ignored. e.g. Specifying `tmp` as well as `test/tmp` without
slashes is redundant, as `tmp` already ignores `test/tmp`, as well as
every other `tmp` and `tmp/`.
yardoc is a config file
stop ignoring overly-specific things

if you need to ignore these things, you should either put them in your
user-wide ignore (like .rbc), or you need to add them to your particular
gem, but not to every gem that exists
Hardcode the list of options for `bundle install --trust-policy`

The reasoning behind this is that OpenSSL gets loaded up in a situation
where we just want to show the help banner for the install command.

Seen as the security policies on the rubygems repo haven't been changed
in over two years, it's safe to just hardcode the values, thus generally
speeding up Bundler commands, most notably in JRuby.

Closes #2950

Conflicts:
	lib/bundler/cli.rb
Add AlmostNoSecurity to trust-policy and fix doc links to Rubygems.
Support read-only git gems (fixes #3092)
Refactor test to use with_read_only helper