Integrations with 3rd-party tools

[MSP-11156](https://jira.tor.rapid7.com/secure/RapidBoard.jspa?rapidView=84&selectedIssue=MSP-11156)

Add badges and integrations for the following:
* Travis-CI
* CodeClimate
* Coveralls.io
* Gemnasium
* Rubygems
* Inch CI
* PullReview