Minor changes to help with external contributions

Hi!

I believe this is a minor pull request.

1) Removed excess whitespace.
This will help when other developers using editors which trim excess whitespace start making pull requests to your project. As those developers make changes to your code, their work may be obscured by line change noise caused by their editor. This makes it difficult for the developer, and for the maintainer, to see what the pull request is actually changing.

2) Added dependencies in a Gemfile
Makes it easier to get started contributing by giving developers one command to install the necessary dependencies.

3) Fixed Rakefile
The default test tasks look for a different set of paths for the test files. I've modified the Rakefile to be able to find your tests.

4) Allow for alternate credentials
I've extracted the values for your internal client ids, api secrets and authorization tokens to environment variables. No sweat for you though, your ids and secrets are the defaults!

Ultimately, I hope this doesn't trample over your development environment, and instead, opens things up for other developers.

Cheers!