Move VERSION to lib/rr/version.rb (fixes #33)

When the Debian wrapper package for RR is installed on a user's machine, the
contents of the lib/ directory are copied to /usr/lib/ruby/vendor_ruby. This
renders the reference to VERSION within lib/rr/version.rb invalid.
Refactor the adapter module shim code a bit
Use #load instead of #hook in the module shim to rescue errors
Add back RR::Adapters::RSpec2 (fixes #34)

This was introduced in 1.0.5 and then removed in favor of the RSpec-2 autohook
mechanism. Unfortunately it seems that the sham_rack started using, and still
uses, this, so we need to bring it back so its tests will run.
Add some internal documentation on developing RR
Add Gemfile.lock to the repo

This is actually okay to do when using appraisal, as we are doing.
Add Rakefile, tests, appraisals, and gemfiles to the published gem (fixes #32)

Both Debian and Fedora wrap RR in a package. These files are necessary for the
package maintainers to run the tests before publishing a new version of the
package.
Move temporary files created during tests to a more portable location
Automatically install deps for a test suite before running it
Add a dev script to build and unpack gem
Add a dev script to regenerate all appraisal gemfiles