Login/Admin menu
Merge pull request #6 from rnowm/datatables

Added datatables plugin fot table sorting
Avoid empty feedback
Move feedback date as first column of the table
Bulk injection preliminar draft
Add excel dependency
IMEI not unique anymore
Get users ordered by email on new device view
Limit max length of fields in user view. Add list of locations
Limit feedback view fields length
Tweaks on bulkinjection script