remove unnecessary rescues

were interfering with debugging because they don't give the proper stack
trace
better (de)serialization for PropMixin
switch to using postgres
fix incorrect variable
add todo re: responding with JSON on errors in send_cart
add pry-byebug
have cart ID be automatically generated in spec
Merge remote-tracking branch 'origin/master' into 79482896_pg

Conflicts:
	Gemfile
	Gemfile.lock
	app/commands/approval/initiate_cart_approval.rb
	app/commands/approval/update_from_approval_response.rb
	spec/models/property_spec.rb
fix cart approval spec file name
don't modify params object
have InitiateCartApproval spec match directory
fix InitiateCartApproval specs
simplify related object creation on carts
don't decorate model on creation
Merge pull request #99 from 18F/initiate_cart_approval_spec

fix InitiateCartApproval spec
Merge pull request #67 from 18F/79482896_pg

[#79482896] switch to using PostgreSQL
Make approval group layouts responsive.
Finish up responsiveness.