reworked js functions

Probably still isn't 100%, but a lot closer than the first couple
commits.

User has to select a start month before the end month will populate.

User has to select a start date before the end date box will populate.

If the end month is is the same as the start month, only >= the start
date will show up to help prevent invalid input.

If the end month is > the end month all days will show up.