fpm: Add protobuf support for FPM.

Code that allows a client to convey routes to a Forwarding Plane
Manager component using protobuf instead of netlink..

  * fpm/fpm.proto

    Protobuf definitions pertaining to the Forwarding Plane Manager.
    In particular, this file defines the AddRoute and DeleteRoute
    messages.

  * fpm/fpm.h

    Tweak FPM message header definition to also allow messages to be
    encoded in protobuf format.

  * fpm/{fpm_pb.h,.gitignore,.Makefile.am}

    Add the fpm_pb library, which contains code for interfacing with
    the FPM using protobuf.

  * configure.ac

    Generate fpm/Makefile.

  * Makefile.am

    Add fpm subdirectory to build.

  * common.am

    Add flags to be used by clients of the fpm_pb library.

Signed-off-by: Avneesh Sachdev <avneesh@sproute.com>
diff --git a/fpm/.gitignore b/fpm/.gitignore
new file mode 100644
index 0000000..b133c52
--- /dev/null
+++ b/fpm/.gitignore
@@ -0,0 +1,15 @@
+Makefile
+Makefile.in
+*.o
+tags
+TAGS
+.deps
+.nfs*
+*.lo
+*.la
+*.a
+*.libs
+.arch-inventory
+.arch-ids
+*~
+*.loT