Add js to show/hide become available

Only show become avaiable calendar if not
currently available is checked

Issue #333
Improve presentation of becomeavailable Issue #333

This is @illmaasterc's commit moved back in.

Move field up to below the parent
  "not currently available"
Use date-popup field type

Issue #333
Add initial condition for displaying the date field.

Initially, only display the the date field if the 'Not Currently Available'
checkbox is checked. RE: Issue #357
Create a 'Current Status' fieldset for the availability checkbox and date field

Within the wsuser module, move the checkbox and date fields to their own
fieldset in order to emphasize them. RE: Issue #357
Add conditional highlighting to 'Current Status' fieldset if user's unavailble.

Highlight the 'Current Status' fieldset, which contains the availability
checkbox and date field, if 'Not Currently Available' is checked.
RE: Issue #357
Set a reasonable? become-available default, change wording, remove date_popup
Merge pull request #357 from illmasterc/issue/333

Improve presentation of become available (Issue #309)