Fix up some errors found by rebar now that we use it for compilation

ebin/rebar.app

@@ -9,7 +9,9 @@
               rebar_log,
               rebar_otp_app,
               rebar_protobuffs_compiler,
+              rebar_port_compiler,
               rebar_rel_utils,
+              rebar_reltool,
               rebar_utils ]},
   {registered, []},
   {applications, [kernel,