Have the MakeMaker shim not recompile without a .mite directory.

This makes a released copy of the code safe even if they have Mite installed.

"mite clean" needed to be fixed to honor --exit-if-no-mite-dir
Have the Module::Build shim not recompile without a .mite directory.
Ensure the build works if Mite is installed but somehow broken.

Not sure how this situation would come up, but there it is.
Merge branch 'issue/33'