SAK-28027 Updated some strings to solve import problems with transifex

git-svn-id: https://source.sakaiproject.org/svn/assignment/trunk@315126 66ffb92e-73f9-0310-93c1-f5514f145a0a
SAK-27975 Visible date is unchecked when the alert comes up

git-svn-id: https://source.sakaiproject.org/svn/assignment/trunk@315127 66ffb92e-73f9-0310-93c1-f5514f145a0a
SAK-26607 assignments post protection

git-svn-id: https://source.sakaiproject.org/svn/assignment/trunk@315128 66ffb92e-73f9-0310-93c1-f5514f145a0a