Pull requests are always on a branch, and this branch
typically is not present on the installer.
This changes means we need to be careful when merging into 3.1
and master, but that's a necessary evil.
The Travis config will now run tests on the following instances
* 5.3 + SQLite
* 5.3 + MySQL
* 5.3 + PostgreSQL
* 5.4 + MySQL
In other words, with the exception of Windows tech (MSSQL + Win server) this is a wide-coverage build config.
