tidying up a bit

- Using [Bundler](http://gembundler.com) to manage installed gems for the project.

- RCov does not support Ruby 1.9.X. The RCov github page suggests using
[SimpleCov](https://github.com/colszowka/simplecov) instead.

- There were also a couple or `require` statements in the Rakefile
that were causing problems (errors, etc) after new gem versions and the
like.

- Removed all trailing whitespace and extra blank lines.

- Including .travis.yml to run the tests using [Travis-CI](http://travis-ci.org)
for Ruby 1.9.3 and 2.0.0.

- Added development dependencies, executables, and exclusions to the
  gemspec.