Update NightCities

After conversing with Alejandro via email this week, he confirmed my own comments that there were problems with NightCities, but didn't have time to update it given timing of his thesis.  I'm a software developer, and offered to help.  I've rolled forward numerous critical fixes that were applied to the LostAtNight app, giving them the same commit names as were used in LostAtNight.  I also fixed a bug when NightCities showed a save error (the buttons were hidden but no reshown), and added a check to prevent saving when no data points have been entered at all.  I've tested and debugged the changes ... on CrowdCrafting.org, there is a test project established that you can re-confirm these updates are working properly: http://crowdcrafting.org/app/MMM_test_nightcitiesiss/
My email: mikemm2000@cox.net