Check of reserved bits in BitMasks

[ajoaoff]

Original issue opened by @erickvermot at kytos#313.

Reserved bits in BitMasks that are not set to 0 should lead to the message beeing rejected (pg52).
Curently, foundation/base/GenericBitMask is not checking for bits that do not have a _enum item.

Maybe implement it in the MetaBitMask, doing something like

USED_BITS = sum([value for key, value in _enum])
RESERVED_BITS = ~USED_BITS

and before the GenericBitMask parses the bits, check that RESERVED_BITS & bitmask == 0.