OSRA-311 Remove trailing .0 from contact numbers

https://osraav.atlassian.net/browse/OSRA-311

 - define NotAFloat column data type in the importer that strips trailing .0
   from strings that otherwise only contain digits
 - replace String with NotAFloat for `contact_number` & `alt_contact_number`
   columns
 - spec & scenario
Merge pull request #241 from NikitaAvvakumov/osra-311-undo-excel-conversion-to-floats

OSRA-311  #Resolve 
Remove trailing .0 from contact numbers