Use a global lock for all HDF5 Tables calls

See https://trac.openmicroscopy.org.uk/ome/ticket/10464
Add lock to HdfStorage in unit tests
Revert "Exclude failing table tests from Travis"

If this doesn't fix the tests but https://trac.openmicroscopy.org.uk/ome/ticket/10464 is no longer a problem it suggests the tests need a more complex locking setup.
This reverts commit 0127af8c3f6ac0ecd08bc735495281ab466afc99
(corresponds to e8baad4c9ad354827342c8107f034001d2fceec9 on develop)
Pass str(path) to PyTables
Revert "Also mark TestTables.testErrorInGet as xfail"

This reverts commit cab835b26fe7f2fe560fa84b8497b3c78ea383b7.
Merge pull request #2783 from manics/rebased/dev_5_0/hdf5_locking-5_1

Use a global HDF5 lock (trac: 10464) (rebased onto dev_5_0)