Separated the page editor.

The page editor is now accessed via ?action=edit.  Nothing was broken
in this commit, but the "preview" action returns a page without the
editor, so the user has to go "back" to the editor.
Fixed edit response

After an edit is submitted, the client is redirected (302) to page so
it doesn't think it needs to resend POST data on reload.
Preview now includes editor.

Fixed the preview response to include the editor.  The destination
URL, however, is for viewing the page (i.e. no action), and the client
thinks it needs to use POST for reloading the page.
Previews now include the editor.

Fixed the "preview" action to say on "page?action=edit" and include
the editor at the bottom of the preview.
Uncommented the git committing code.

Uncommented the code that commits edits.