Remove redundant loading of pg.

The file has been removed in AR-JDBC 1.3.0 and the library
should properly autoload when required from the Gemfile.
Update travis-core for HipChat API V2 support
Correcting link location
Merge pull request #27 from comjf/copy-fix

Correcting link location
Bump travis-core.

Includes a fix for enqueue timeouts, new event handlers for Slack.
Bump travis-core.

Includes event handler for Slack.