[WIP] 0.24.0 release and testing

[jchodera]

@andrrizzi : I'm currently running all the tests on this proposed release.

[jchodera]

Only one test failure on lilac, and this seems to be due to a problematic failure criterion:

======================================================================
FAIL: Test that the harmonic restraint simulated free energy equals the standard state correction
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Traceback (most recent call last):
  File "/home/chodera/miniconda/lib/python3.6/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/lila/home/chodera/github/choderalab/yank/Yank/tests/test_restraints.py", line 229, in test_flat_bottom_free_energy
    general_restraint_run(options)
  File "/lila/home/chodera/github/choderalab/yank/Yank/tests/test_restraints.py", line 209, in general_restraint_run
    assert np.allclose(DeltaF_restraints, DeltaF_simulated, rtol=2*dDeltaF_simulated), 'Standard state correction is inaccurate.\n' + msg
AssertionError: Standard state correction is inaccurate.
Computed:     0.000          kT
Actual:       0.000 +-    0.000 kT
ERROR:        0.000 +-    0.000 kT


----------------------------------------------------------------------
Ran 511 tests in 1745.561s

FAILED (SKIP=1, failures=1)

@andrrizzi : If this looks good to you, can you merge this and cut a new release with these release notes? If you have time, you can cut a new conda release to as described in #1146

[andrrizzi]

On it!