made  available to eval, due to which some tests were failing
Wrote tests for InvalidHasProvidedInARole
replaced croak with throw_exception
Wrote exception class InvalidHasProvidedInARole
Changed BadHasProvided to InvalidHasProvided
Changed BadHasProvided to InvalidHasProvided
Changed BadHasProvided to InvalidHasProvided
Replaced throw_error with throw_exception
added tests for exception in Moose::Role
Wrote exception classes for MetaclassIsAClassNotASubclassOfGivenMetaclass & MetaclassIsNotASubclassOfGivenMetaclass