Add ability to log time worked using decimals

When logging time worked, jira's time entry uses w,d,h,m as short hand for weeks, days, hours, and minutes; however, only integers can be used for data entry.

For example:

In order to enter 1 hour and 30 minutes, you must enter 1h 30m. It would be helpful if that same amount of time could be entered as 1.5h.