Enable GSL tests (reverts part of changeset 88c50cd078dd).
Enable GSL tests (reverts part of changeset 88c50cd078dd).

mjbshaw/Eigen,rotorliu/eigen,rotorliu/eigen,madlib/eigen_backup,mjbshaw/Eigen,mjbshaw/Eigen,mjbshaw/Eigen,rotorliu/eigen,rotorliu/eigen,madlib/eigen_backup,madlib/eigen_backup,madlib/eigen_backup