Extended mutually_exclusive, exactly_one_of, at_least_one_of to work in group

change mutually_exclusive to work in scope
change exactly_one_of to work in scope
change at_least_one_of to work in scope
all of those methods changed to work for Hash and Array
all of those methods changed to work for requires and optional scope
add and change specs
Merge pull request #774 from ShPakvel/bugfix_for_699__scoped_mutual_methods

Bugfix for issue 699 - scoped mutual methods