When calculating ranges from JIRA Dates, the range is incorrect if no time is specified

If you specify a range from one Date Field to another Date Field, Team Calendar will display the range incorrectly.

Steps to Reproduce

1. Create a custom field type called "PlannedStart"
2. Create a new issue that uses this custom field, and:
   1. Set the "Due Date" to "15/01/2015" (15th Jan 2015)
   2. Set the "PlannedStart" to "13/01/2015" (13th Jan 2015)
3. Display a date range for this issue in Team Calendar

Expected Results

Team Calendar should display a range from the 13th to the 15th

Actual Results

Team Calendar starts the event at a certain time on the 13th (in my case it was 11:00AM), and the date range is subsequently longer:

Workaround

Use a Date/Time picker for the fields to be shown in Team Calendar. When a Date/Time picker is used, Team Calendar will display the correct range:

This appears related to TEAMCAL-2718, but I'm raising it as a separate issue in case this is not the same cause.