qpid-proton: new package

[Thomas:
   - Do not define QPID_PROTON_VERSION_MAJOR, and use proto-* instead,
     as suggested by Arnout.
   - Use QPID_PROTO_VERSION in QPID_PROTON_SITE, as suggested by
     Arnout
   - Remove useless comma in the openssl test, as suggested by Arnout
   - Change the post install target hook to remove the
     /usr/share/proton-*/ directory entirely, and not just the
     examples, since it only contains some license and documentation
     files.]

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>