Fixed rubinius metagem description.
Updated CI specs to RubySpec 47a1fc63.
Updated MSpec source to 439b4fa1.
Fixed Thread#priority, #priority=.

Since setting the Thread priority is already a no-op and Thread
priorities are essentially meaningless, we simply make it an
attribute. This also fixes a segfault that occurred because the
priority of a #join'd thread could be retrieved.
Fail if gem unpack fails.
Removed obsolete deviates block.
Return method name from Module#define_method.
Fixed Module#define_method spec failing on 2.1.
Update CI tags.
Updated MSpec config.
Removed version directory from CI tags.