Accept the following formats for the timelog "hours" field: 1h, 1 h, 1 hour, 2...

Accept the following formats for the timelog "hours" field: 1h, 1 h, 1 hour, 2 hours, 30m, 30min, 1h30, 1h30m, 1:30.
Also accept 1,5 for 1.5 hour (closes #975). Note that 1.5 is still equal to 1h30 and not 1h50 (#947).

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1320 e93f8b46-1217-0410-a6f0-8f06a7374b81