Work on prestudy:
   - Created subsection about Waterfall model
   - Several changes in the existing subsections about development models
   - Started work on existing solutions. Changes in the section about Google play.
Further work on prestudy
   - Removed App Store from prestudy
   - Modificatin on the section about Google play
Over the air transfer #23

Over the air transfer, Pebble
Image reference, typos #23
Merge branch 'master' into prestudy
Merge branch 'prestudy' of https://github.com/Prosjekt2-09arduino/docs into prestudy
Adjust image size, typos #23
Merge pull request #26 from Prosjekt2-09arduino/prestudy

Prestudy