On postinstall, run bower install, not bower update.

I think this will fix the broken build, although I'm not sure why the change was made. Commit 922dda732bfe9 suggested that it was to fix the Travis build, but I don't see how.

Edit: to clarify, I mean I don't understand why bower update would be necessary on a Travis build. I assume Travis cleans up the working area between runs. Sorry if this is the wrong approach to the problem.

/cc @krisselden