Add Braintree to Gemfile.
Modified user model, added braintree initializer, and added braintree id to user table migration.
Added SimpleCov.
Added Braintree Environment variable handling to h.sh.
Merge branch develop into branch braintree.
Update README and refactor User model. Add BrainTreeRails initializers.
Remove call to tag_helper_ext from https://github.com/lyang/braintree-rails-example/blob/master/lib/rails_ext/tag_helper_ext.rb
Added try for to_sym in Braintree initializer because Travis doesn't have any environment variables.
Update README.md and attempt to fix Travis fail by adding a default env var for Braintree's environment (sandbox).
ACL rules for Crops and CropYields.