Lots of layout things

Not everything that I wanted to finish is done, but I wanted to make a PR to merge some things in so:
 a) people know what fragments already exist in terms of navigation, so we can avoid some redundancy
 b) reduce # of merge conflicts omg

Things I did:
- merged AccountRegistration and EventRegistration together.  I feel like there is enough space to do this without being overwhelming, and since we're only pushing data to Salesforce at the end, this seems okay now.
- created assets and made custom EditText, Spinners, Checkboxes, etc.
- Sidebar buttons now work and will move to the correct fragment in the backstack if possible
- created fragments for Selection, Search and SearchResults, and created appropriate assets

It still doesn't really look the way it's supposed to, but eh, its getting there.
Document the constructor