All: Drop support for IE7

Fixes #9838
Closes gh-1365
Build: Upgrade to commitplease 2.0.0

commitplease now accepts "[tmp]:" and similar to temporary commits,
useful while updating pull requests that are squashed later.
Selectmenu: Remove broken tabindex code
Datepicker: Fixed month names and firstDay value in Arabic locale

Fixes #10035
Closes gh-1246
Build: Upgrade to grunt-git-authors 2.0.0 and add update-authors task

Closes gh-1378
Tests: Adding missing dependency
Tests: Removing unused visual theme test
Theme: Change default widget font-size to 1em

Fixes #10131
Closes gh-1374