Date picker fixes

- use user's timezone when asking for date and time
- automatically build jQueryUI DatePicker format starting from the php date format
- parse the received date string accordingly to the used format
Bugfix
Remove special case 'DATE_PICKER' from tests

We now have to use DateHelper->getJQueryUIDatePickerFormat()
Show date/time in current timezone
Merge pull request #1782 from mlocati/fix-jqueryuidatepicker

Date picker fixes
Fix: can't use select type attributes for generate sitemap.xml job
Merge pull request #1817 from hissy/sitemap_job

Fix: can't use select type attributes for generate sitemap.xml job
Fix time setting issues on Add access entity dialog
Merge pull request #1820 from hissy/elements-timesettings

Fix time setting issues on Add access entity dialog
Fix upgrade problem from 5.5.x to 5.6.x
Merge pull request #1822 from hissy/upgrade

Fix upgrade problem from 5.5.x to 5.6.x