[GH #877] Removed @revision@ text in myconfig output

The @revision@ information was only useful back in the Subversion days and
consequently (since we are now using Git) isn't necessary anymore.
[GH #877] Removed auto::revision from configure steps

We wish to remove the Parrot::Revision functionality, so this dependence
within the configure step needs to be removed.
[GH #877] Removed Parrot::Revision dependence in Configure.pl

Since we wish to remove Parrot::Revision, we therefore no longer need to
update the Parrot revision number when configuring.
[GH #877] Removed config/auto/revision.pm and its tests

In issue GH#877 the old Parrot::Revision code should be removed.  This
removes the configure step and its associated tests.

The references in t/configure/testlib/*defectivefoobar have also been
removed.
[GH #877] Removed Parrot::Revision

Now that the dependencies on Parrot::Revision have been removed, it's now
possible to remove Parrot::Revision itself.  The tests pass, so all is good.
Merge pull request #945 from paultcochrane/ptc/remove_parrot_revision

[GH #877] Remove Parrot::Revision