Code changes:
 - Added two new enum values to ValidationResult - IS_POSSIBLE_LOCAL_ONLY and
   INVALID_LENGTH. Added more documentation to the existing values; see the
   javadoc for when these are going to be used. Note that the API for
   IsPossibleNumberWithReason has not yet been changed to return these values.
   IS_POSSIBLE_LOCAL_ONLY will be returned for some values which currently
   return IS_POSSIBLE, and INVALID_LENGTH will be returned for some values which
   currently return TOO_LONG.
 - Fix for isNumberMatch to ignore the numberOfLeadingZeros field when comparing
   numbers unless hasItalianLeadingZero is true, and to consider default values
   to match the same value when explicitly set for these two fields. This fix
   shouldn't be needed for anyone correctly creating phone numbers using "parse"
   as recommended.
 - C++ only: Fix for ExactlySameAs when comparing phone numbers to include
   comparison of the number_of_leading_zeros field.
 - C++ only: Updating maximum length for NSN to be 17 (matches Java and JS)