Merge pull request #4 from szilardhuber/master

Added "real class" to encapsulate protobuf expression message.
adding pull helper script
pull.sh makes sure we update submodules properly
use the C++ ZMQ binding from git submodule; fixes Mac build
integrating/adding gtest
align virtdb_fdw with the latest proto changes
gtest now builds
added a very simple gtest based test
Merge pull request #5 from dbeck/master

integrated google test and added a simple test case
Fixing shared_ptr usage.