Change MRI Ruby version in examples from 237 to 327
Merge pull request #28 from mhutchin/change237to327

Change MRI Ruby version in remaining examples from 237 to 327
Use sha1 instead of md5.
Website must be first.
Link to the new Ruby Installation wiki pages.
Added RHEL / CentOS.
Added `vagrant box add` commands for each VM.
Added ruby-version by @wilmoore to the Alternatives list.
Began refactoring setup.sh (issue #31).
Adjust a log message.
Compact some lines.
Decouple the removal of GEM_HOME and GEM_ROOT (just in case).
Rubies are now stored in /usr/local/rubies/.
Revert "Decouple the removal of GEM_HOME and GEM_ROOT (just in case)."

* Why do I keep wanting to do this. The logic of chruby dictates that
  GEM_HOME and GEM_ROOT are to be coupled.
Support auto-detected installed Rubies (issue #29).

* Search in /usr/local/rubies, /opt/rubies, ~/.rubies.
* Only allow directories which contain bin/ruby.
minor-readme-tweaks: corrects a typo and swaps ordering of feature line item.
Merge pull request #33 from wilmoore/minor-readme-tweaks

Corrects a typo and swaps ordering of feature line item.
configurable-make-test: Allows `make test` to be run with `SHUNIT_BIN`.

- Contributors may have installed shunit2(1) to somewhere other than
  `/usr/share/shunit2/shunit2`.
- Allow `SHUNIT2_BIN=$(which shunit2) make test`.
- Default to `/usr/share/shunit2/shunit2` if `SHUNIT2_BIN` is not given.
Renamed SHUNIT_BIN to SHUNIT2 and default it in test/helper.sh.
Removed /usr/rubies and /usr/local/rubies to comply with FHS (issue #36)