Added Python 3.4 and PyPy to the build matrix
Added Python 3.4 and PyPy to the build matrix

Also --use-mirrors is deprecated. Use travis_retry instead in order to avoid build failures caused by network problems.
julianhille/mongomock,marcinbarczynski/mongomock,mdomke/mongomock,chartbeat-labs/mongomock,akun/mongomock,magaman384/mongomock,drorasaf/mongomock,vmalloc/mongomock,StarfishStorage/mongomock