Saving answers of trip questions to local database.

Since trips may not always be uploaded immediately, the answers to the
trip questions must be stored along with the data for the trip, until
the trip can be uploaded.
Completed implementation of trip questions

Completed implementation of trip questions, and also did some major work
on transitions between activities (both forward and backward through the
activity stack).
Merge pull request #30 from mafiglio/Feature_TripQuestions

Feature trip questions