GCI-31: Navigation bar revamp

Implement [GCI-31](https://issues.openmrs.org/browse/GCI-31) / [ID-68](https://issues.openmrs.org/browse/ID-68): Navigation bar revamp. I've also restyled some of the header, it now looks like this:

![screen shot 2014-12-07 at 3 37 30 pm](https://cloud.githubusercontent.com/assets/5162342/5333011/268ff500-7e27-11e4-9937-9aad96009abc.png)

The navigation bar have the current options, just new styling.

Feedback appreciated!