Corrections in field extension methods

[OndrejValenta]

• AddNumberField
  • min, max values should be of type double
  • default value should be of type string
• AddTextField
  • add missing max length parameter
• AddChoiceField
  • parameter choices change to IEnumerable so it can accept other collection types
  • choice items are not created properly, they are all combined into one value
• AddLookupField
  • add new overload methods to use list guid instead of list title and to use web guid and list guid so we can create cross web lookups