Remove simple_form errors on new_activity_session, modify flash notices
Fix activity log so Javascript sorting tests pass, table does not display if no activities logged
Add activity names to Categories view

Update feature spec, write test & method for “activity_names”, add
activity_names to table in view
Change flash to flash.now globally

Also fixed plurals/singulars in messages & widened notice <div>
Add top bar bottom margin, fix darken on My Account & Sign Out links