Added the Hybrid map type and cleaned up the constraints on the Settings page

The Settings page now allows for selection of the Hybrid map type in addition
to the others, and while I was updating the story board, I made sure that the
constraints were set up properly for everything to resize.  That included
changing the text of the "Automatically center map on GPS coordinates", which
was too long for the smaller iPhone screens.  Now it's shorter text with an
small text size annotation below it.
Some minor fixups on constraint errors
Added Grace's new app icons!
Merge remote-tracking branch 'remotes/upstream/master'
Merge pull request #24 from agricocb/master

 Added the Hybrid map type and cleaned up some constraints, added Grace's icons