Merge pull request #1760 from benjaoming/patch-1

cms_toolbar templatetag library is not in 2.4.x
first draft
Added logging to management moderator on command, exception handling on publish so the migration continues and logs the exception
Merge branch 'develop' into frontend_reversion
added migration field
first draft for undo
undo working :)
redo working
Explain how to combine hvad with the admin app
Merge pull request #1776 from patrys/patch-1

Explain how to combine hvad with the admin app
Merge pull request #1765 from TAMUArch/support/2.4.x

Exception handling in management moderator command for 2.4.x
Explicitly pass the language

This avoids depending on a particular layout of the admin screen.
Second place where the same code is used
Use type-safe comparisons
Merge pull request #1778 from patrys/language-fix

Explicitly pass the language
docs, undo and redo grey out and clearing of reversion_id from page
tests for undo redo
fixed tests
Merge pull request #1771 from digi604/frontend_reversion

Frontend reversion integration with undo / redo
Merge branch 'support/2.4.x' into develop

Conflicts:
	cms/templates/admin/cms/page/widgets/installed_plugins_inc.html