Revert Revert "Add support for ci_access_token and :travis_pro"

This reverts commit 3922cd17fee101ee9804f3bc483d4b67bf22c80b.
Add Travis CI Pro section to README
Add an option to define the output directory for cobertura xml reports.
Merge pull request #36 from dlackty/travis-ci-pro

Supports Travis CI Pro again
Merge branch 'master' of https://github.com/venmo/slather

Conflicts:
	lib/slather/project.rb

Fixed.
Fix specs.