Enable rspec tests with reproducible test harness

Before this commit: chocolatey_spec.rb exists but is not runnable
After  this commit: run `rake spec` to perform unit tests

More info:

- Move existing chocolatey_spec.rb to a subdir so that we can
  keep rspec-related files in a single tree

- Use `bundle install` to add gem dependencies

- Configure this repo to push to tracking branch by default
Use travis-ci.org for continuous integration

Enable service hook to let travis-ci build the project [1].

[1] http://about.travis-ci.org/docs/user/getting-started/
Fix unit test to reflect current provider code

Commit 3ab91639 removed line feed from version number to fix
"version number resolution" in the provider code, but did not
change the associated rspec example.

This commit updates the rspec example to be consistent with
commit 3ab91639, and the unit test now passes:

Puppet::Type::Package::ProviderChocolatey when fetching a package list should return installed packages with their versions