Bump codecov to latest version
Bump codecov to latest version

Codecov 0.1.x were yanked from rubygems, causing installation of
cs_comments_service to fail.

The changes here were created by running `bundle update codecov`.

Fixes #322

edx/cs_comments_service,EDUlib/cs_comments_service,EDUlib/cs_comments_service,edx/cs_comments_service,EDUlib/cs_comments_service,edx/cs_comments_service