Merge obs_lsstSim tests into obs_base

obs_lsstSim has some tests in it: those should get lifted into obs_base and deleted (or just deleted, if there is already an equivalent test in obs_base), and test_obs_lsstSim.py should be created to inherit the obs_base testing framework.

Once the new tests are merged in, the other obs packages that depend on obs_base should have their test setUp updated to reflect the new tests.