whsc: ask for the approver's email address
whsc: default the approver's email address to the last cart
add expense types to WHSC form
Merge pull request #143 from 18F/expense-type

add expense types to WHSC form
Merge remote-tracking branch 'origin/master' into whsc-approver

Conflicts:
	spec/features/whsc_proposal_spec.rb
Merge pull request #141 from 18F/whsc-approver

[#84702440] add field for approver email to WHSC form
refactor cart mailer
only show link to view request in browser w/ flag enabled
remove empty rejection mailer
test that the approver is notified on rejection
Merge pull request #144 from 18F/rejection

[#82298968] verify that rejection email is sent
[#85041962] Added WHSC Email template
[#85041962] Updated specs for mailer
[#85041962] Move property exclusions for custom templates into decorator
[#85041962] Removed template logic pertaining to web delivery
[#85041962] Added email status partial to WHSC email