Update for 5.0 branch (DOI field for publications added, assessment UI for students added, some installer and updater problems fixed, UI for jquery UI dialogs added, several small bugfixes). This is teachPress 5.0alpha9.

git-svn-id: https://plugins.svn.wordpress.org/teachpress/branches/5.0.x@978264 b8457f37-d9ea-0310-8a92-e5e31aec5664