Disable get_impl unsigned implementation for T = bool.
Disable get_impl unsigned implementation for T = bool.

This should have been being selected by bool, but I erroneously thought
that std::is_unsiged<bool>::value == false. It is true.

So is std::is_arithmetic<bool>::value, so the only way I know how to
disable this is by comparing directly against bool using std::is_same...

This should fix issue #39.

skystrife/cpptoml,skystrife/cpptoml