Solved some table issues
Updated bill table
Merge branch 'master' of https://github.com/AllanLeon/TaxBilling into SortBillTable
Changed cashPopUpMessage to controlCodePopUpMessage
Changed row color
Created NitHeaderClickedListener class
Renamed getBillList method to getBills
Added IDs to the headers
Created BillNumberHeaderClickedListener class
Created AuthorizationNumberClickedListener class
Renamed some classes and created DateHeaderClickListener class
Created AmountHeaderClickListener class
Created ControlCodeHeaderClickListener class
Implemented listeners on the table
Updated control code EditText to accept letters
Deleted useless lines
Merge pull request #20 from AllanLeon/SortBillTable

Merged sort bill table branch