Update gtest

Previous method to use gtest as shared library is too complex. Instead,
we can simply it by using the static library libgtest.a. Procedures to
generate the libgtest.a is as follows:

$ cd cards/thirdparty
$ unzip gtest-1.7.0.zip
$ mv gtest-1.7.0 gtest
$ cd gtest
$ g++ -I . -I include/ -pthread src/gtest-all.cc -c
$ g++ -I . -I include/ -pthread src/gtest_main.cc -c
$ ar -rv libgtest.a gtest-all.o gtest_main.o
$ #Remove everything except include and libgtest.a