Replaced remaining #assert_tag with #assert_select.

git-svn-id: http://svn.redmine.org/redmine/trunk@13624 e93f8b46-1217-0410-a6f0-8f06a7374b81
Clear @spent_hours on reload (#18410).

Patch by Ondřej Ezr.

git-svn-id: http://svn.redmine.org/redmine/trunk@13625 e93f8b46-1217-0410-a6f0-8f06a7374b81