Change `.bar-title` to `.bar-nav` in template.html

Update template.html to be in line with changes introduced in [de819933614a94e66603f1609f4d81e4dc2517a6](https://github.com/maker/ratchet/commit/de819933614a94e66603f1609f4d81e4dc2517a6)

Tested in Chrome 30.0.1599.69 and iPhone 6.0 simulator.