Refactor controller to make verify method easier to read
Refactor controller to make verify method easier to read

As the verify method was starting to do too many different things, it was split out into separate methods for depending on sponsor or signature count.

joelanman/e-petitions,telekomatrix/e-petitions,StatesOfJersey/e-petitions,ansonK/e-petitions,oskarpearson/e-petitions,unboxed/e-petitions,oskarpearson/e-petitions,oskarpearson/e-petitions,telekomatrix/e-petitions,StatesOfJersey/e-petitions,alphagov/e-petitions,joelanman/e-petitions,unboxed/e-petitions,ansonK/e-petitions,ansonK/e-petitions,telekomatrix/e-petitions,StatesOfJersey/e-petitions,alphagov/e-petitions,unboxed/e-petitions,joelanman/e-petitions,alphagov/e-petitions,unboxed/e-petitions,alphagov/e-petitions,StatesOfJersey/e-petitions