Merge pull request openwebwork#948 from openwebwork/WeBWorK-2.15

WeBWorK-2.15-beta

Merge pull request openwebwork#817 from jwj61/hotfix-keywords

Fix keyword searching

Merge pull request openwebwork#796 from openwebwork/hot_fix_sendmail_…

…notification_bug

Hot fix sendmail notification bug

Merge pull request openwebwork#697 from openwebwork/release/2.12

Release 2.12 Pull Request

Merge pull request openwebwork#695 from d-torrance/remove-pointgraph.…

…save

Remove file PointGraph.save.

Merge pull request openwebwork#651 from openwebwork/release-2.11

Release 2.11 Pull Request