Build script and hockeyapp

* Add Hockeyapp.net SDK for distribution and crash reporting
* First pass at a build script that dumps an ad-hoc signed ipa
  file in the build directory and passes in Hokeyapp.net API
  keys  to the build from a private repository.
* Automatically upload build to hockeyapp.net if apikeys.txt exists 
  in dependencies directory
* Will rebase this PR on master once before merging
  after firmware update branch is merged since the build
  script depends on updatedepends.sh being run.
Thinking that there should be a (possibly optional) commit after this step.

Otherwise, the commit pointed to by CURRENT_GIT_HASH would show a different build number to that in the binary.