qc: add quickcheck as a dependency
qc: expose 0x01.Wildcards parse and marshal
qc: Implement 0x01.Wildcards roundtrip tests

    parse . marshal == id
qc: note OF0x01.Wildcards fields that are unsigned
qc: Move OF0x01.Wildcards arbitrary to module

As per the discussion on #3, arbitrary instances will reside in the
module where the datatype it's testing resides. Because of this, the
quickcheck library is now a dependency for the openflow library, as well
as the test suite.
qc: remove unused module alias
Revert "qc: remove unused module alias"

This reverts commit db9ae568f9cf4fee3f0037c3cd9c6a95a43ccb4d.
Revert "qc: Move OF0x01.Wildcards arbitrary to module"

This reverts commit 53f84d19417700bed49e62e0b3eb707e96d3e3b2.
qc: move quickcheck code to sublibrary

Use the OpenFlow0x01_Arbitrary signature to build all the components of
a roundtrip test. Then it will be straightforward to run a test using
the values defined in the module that conforms to that signature:

    module M : OpenFlow0x01_Arbitrary

    quickCheck M.arbitrary M.to_string M.parse M.marshal
Merge pull request #3 from frenetic-lang/quickcheck

LGTM