Revert "Configure Travis to use @knalli's Bower fork"

A fixed release of Bower is now available via npm.

This reverts commit 67f5564e04f48f52517caebcc24bd2e20e7d2e35.
Make Bower ~1.3.2 a min requirement (npm + Travis)

We need at least version 1.3.2 to avoid a race condition:
https://github.com/bower/bower/issues/1211

https://github.com/bower/bower/issues/933
https://www.openproject.org/work_packages/5645

Signed-off-by: Alex Coles <alex@alexbcoles.com>