Update version number to 0.3.4.
Update version number to 0.3.4.

Change-Id: I06d3cdc10d7a3c9a0eb1496217a260ffc1a49cb4

cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp,cloudendpoints/esp