Release 12MAR18 - with errata bug fix

Merge pull request #552 from openstax/errata-blank-email

Reverse code to blank Errata email on Save as New until after Wagtail upgrade

Release 12MAR18

2.2.0

Create field for assessment id (#551)

Release 11/20

2.1.0

Add shared Errata page template (#523)

Hotfix for TOC numbering

Remove section numbers (#515)

* Remove section numbers from TOC

* Remove dividers from TOC

Hotfix for CNX collated book TOC

Merge pull request #513 from openstax/profile-model-admin

Add admin for account profile

Hotfix for unicode issue

Merge pull request #511 from openstax/profile-admin

Add user profile to admin interface