Attach message to multiple financial aid applications
Field changes for #196

* Rename Travel Prefered Disbursement field to Disbursement Notes
* Remove fields:
  * Travel signed
  * Travel check number
  * Tutorial amount
Document how sending email to financial aid applicants uses templates works.

Part of #196.
Merge pull request #201 from caktus/feature/196-finaid-email-doc

Document how sending email to financial aid applicants uses templates works.
Merge pull request #191 from caktus/feature/191-finaid-mass-note

Add mass note to finaid apps
Change migration to use rename column instead of deleting and adding
Increase height of registration iframe

The height of the tallest registration page is currently 1255.
That needs to fit into the iframe without scrolling, so set
iframe height to 1400 to leave a little room for the page to
get a little bigger.
Merge branch 'feature/196-finaid-feedback' into develop
Link to Read The Docs from README
Remove div12 to center registration form on page
Merge branch 'feature/202-increase-registration-iframe-height' into develop
Merge branch 'develop' into staging