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
add a 'flow' enum to approval_groups
add SimpleEnum for Rails 4 compatability
clean up approval group form indentation
Merge remote-tracking branch 'origin/master' into 79249190_linear_group

Conflicts:
	Gemfile
	Gemfile.lock
add form option for selecting linear flow
use built-in enum support form rails 4.1
validate presence of ApprovalGroup#flow
simplify select options helper
First step of CSS reorg.
finish reorg. Center popup correctly.
Fix mailer template base.
Make positioning use variables, like it should.
Merge pull request #85 from 18F/81305030_reorg_css

81305030 reorg css