Merge pull request #7 from dmeyer3691/master

Merging changes made during code review on 6/18/14
remove `data_`
defined __repr__ for freshdata.source
organizing test structure
Changed base url for us_census to include a final / in both files. Added a function to open a browser window to the api_url. Added some logic in the manager.get method to open browser if key is required and not present. Implemented the ping method. Have not tested the ping, browser open method.