changed sequence block duration unit from minutes to days. refs #3781
added entry to language files.
relabeled duration input field. refs #3781
added translation keys for "day" and "days". refs #3781
relabeled unit for duration output in sequence block view from hours to days. refs #3781
Merge pull request #177 from ilios/rb2.3

reintegrate release branch rb2.3 into master