Navigation Bar 

Navigation bar implementation wired in. Interacts properly with the progress bar now so that it can be enabled/disabled and takes the place of the progress bar when enabled.
Hey, have you tested that this doesn't inadvertently expand repeats? It's surprising to me that some of the code that was removed in https://github.com/dimagi/opendatakit.collect/pull/34 is back (like onCurrentScreen). Wondering if there was a bad merge.