Show searched dates in date fields

* Allow no operator to be selected to keep previous one

Adding users still needs work

Better error handling: still needs fixing

Minor cosmetic changes

Fixed delete WiSP user to delete group associations

More error checking

Failing to insert user, needs fixing

* Changed attribute name SMRadius-Capping-Time-Limit to SMRadius-Capping-UpTime-Limit, this makes way for another feature to be added soon