Update INSTALL.md
Update INSTALL.md

updating to reference preferred way to run tests.

Former-commit-id: c40e416a313d94443c37014ff648059cf31c9687 [formerly 235787aeac70db7642c6c60b73f66e97014077e3] [formerly f45a4fa51651844c3bdf5e3b1050052b74f51755 [formerly af2799f99815880f52764fc2b3fcff562b5da459]] [formerly 494cf50e6eef020faf12d8439215e2e695e6ab69] [formerly a772e645cf5aa75c51c722811101753dac8b054d [formerly 5fc9e92c01ccd4a62d6d3f6312ce1094d5dee457]]
Former-commit-id: a772e645cf5aa75c51c722811101753dac8b054d
Former-commit-id: 5ad8e8c8beb26469e377874e8795ae84e850476d
Former-commit-id: 85fc115a2d8c9f5630f11f4e9a4d0e2cba4c2483 [formerly cea7a2bc9f4372682b1f1d6566ace6a0d36828b3]
Former-commit-id: a4201768ccbb9818f46881076604cecb3a012cc2
kaustubhcs/PyOpenWorm,hnunner/PyOpenWorm,gsarma/PyOpenWorm,travs/PyOpenWorm,openworm/PyOpenWorm,openworm/PyOpenWorm,gsarma/PyOpenWorm