Document how to set up Rspec for testing

[monfresh]

Please add documentation detailing what's needed to be able to run tests with Garner. Thanks!

[monfresh]

I think I figured it out. Tests are passing now after adding these 2 lines to my config.before(:each) block in spec_helper.rb:

Garner.config.reset!
Garner.config.cache.clear

Is this all that's needed? If so, I can submit a documentation pull request if you want.

[fancyremarker]

@monfresh: We actually clear the entire underlying cache (in our cache Rails.cache.clear), but your approach is more correct for the specific case of Garner. Yes, please submit a pull request and I'll merge. Thanks!