Fixed CMakelist to work with GMock

Feel free to ignore changes to SoundexTest.cpp but the changes to CMakeLists allows it to work with GMock 1.7.0, assuming that the following environment variables are set:

export GMOCK_HOME="$HOME/gmock-1.7.0"
export DYLD_FALLBACK_LIBRARY_PATH=$GMOCK_HOME/lib/.libs:$GMOCK_HOME/gtest/lib/.libs:$DYLD_FALLBACK_LIBRARY_PATH