Add gtest 1.7.0
Merge commit '5585e1c1439d318ca5d741cfa436f548d850c22c'

Conflicts:
	src/extra/gtest/Makefile.in
On travis, run the 'make check-devel', not 'make check-all', as the later takes
longer than 50 minutes, in which case travis halts the testing.