Added tileLayer options into configuration
Toggle to a secondary layer if out of bounds

If our custom tiles don't cover the area then we switch based on the
bounding box of the tiles we generate.
Added map options into main config file
Read map options from moxie options
Added comments to map layer toggling code

Clarifies the way we use this secondary layer and when we add it to the
map.
Merge pull request #30 from ox-it/map-secondary-layer

Map secondary layer