Add legal documentation to MyUSA & link from footer

This addresses #49 and #108.  It posts the legal docs
as markdown, and then processes them into one legal.md file
using a rake task.  From there, aglio turns the markdown
into html, and puts it in /public/legal.html.

aglio part of our rails views, but we're leaving that for
another day.
SES and Google secrets & settings
set From: and Reply-To: for outbound mail
Add tests for revoke app

These tests are the remaining code from PR #208.
Test Reply-To: as well
Merge pull request #252 from 18F/feature/revoke-tests

Add tests for revoke app
Merge pull request #251 from 18F/hotfix/email-settings

Hotfix/email settings
Merge pull request #247 from 18F/feature/legal

Add legal documentation to MyUSA & link from footer
clean up unused/redundant code in sign_in_spec
Merge remote-tracking branch 'origin/devel' into feature/user_audit

Conflicts:
	spec/features/devise/sessions/sign_in_spec.rb