Allow binary == 0.7.*
C.D.P.Internal.Primtives.mask does not work correctly if unmask is
called by a process other than the one that called mask. An example
of this behavior is in callLocal below. The expected behavior of test is this:

Wed May  8 22:50:01 UTC 2013 pid://127.0.0.1:8080:0:3: hi
Wed May  8 22:50:01 UTC 2013 pid://127.0.0.1:8080:0:4: hi
Wed May  8 22:50:01 UTC 2013 pid://127.0.0.1:8080:0:5: hi

Each say is emitted by a distinct process. However, the observed
behavior is given here:

Wed May  8 22:38:57 UTC 2013 pid://127.0.0.1:8080:0:3: hi
Wed May  8 22:38:57 UTC 2013 pid://127.0.0.1:8080:0:4: hi
Wed May  8 22:38:57 UTC 2013 pid://127.0.0.1:8080:0:3: hi

Note that the say called within callLocal thinks it is running
in the same process as its parent, even though there is a
spawnLocal between them.

This commit fixes this behavior.
Ensure that unmask operates on the correct (scoped) LocalProcess

Previously the LocalProcess from the outer (masked) scope was passed to
runLocalProcess, which could lead to catastrophic changes in runtime
behaviour, e.g., receiving (esp. on typed channels) blocking indefinitely
since the the caller would be referring to someone else's mailbox.

Reported by Jeff Epstein, Facundo Dominguez.
Fixes pull requests #138 and #139.