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.
Tweak sample commit message.

This admittedly microscopic change encourages best practices as discussed by
@tpope here:
http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
Merge pull request #1882 from kytrinyx/tweak-default-readme

Tweak sample commit message.
make tests pass under travis.

sudo tests were failing under travis because they were not
being run as root.  this change runs the root tests as root,
and chowns the tests' "tmp" directory back to the original
user to allow the subsequent 'realworld' tests to pass.
Merge pull request #1891 from echohead/bundler

---

sudo tests were failing under travis because they were not
being run as root.  this change runs the root tests as root,
and chowns the tests "tmp" directory back to the original
user to allow the subsequent realworld tests to pass.
initial work on ruby_version dsl
refactor ruby version into it's own class
remove focusing on tests
fix some whitespace
add SystemRubyVersion to check against
ruby version check for bundle#install
ruby version check for bundle#check
ruby version check for bundle#update
refactor ruby version check tests
ruby version check for bundle#show
ruby version check for bundle#cache
ruby version check for bundle#pack
ruby version check for bundle#exec
ruby version check for bundle#console and Bundler.setup