Changed the max zoom level to 21, but made sure that highest zoom level TileUtil.js will cache is 19 because that is the highest OSM has for download.  I also added a null check to FailSync for when removing from mediaToSend.  I also fixed a bug where a layerSchema was being created without the layerid.
Merge branch 'FailedSync-rebased' of https://github.com/ROGUE-JCTD/Arbiter-Android into FailedSync-rebased