REL: disallow broken PyCifRW 4.3.0.

PyCifRW 4.3 crashes on import in Python 2.7.3.
Request a different version of PyCifRW as our dependency.

TODO: revert this once PyCifRW is fixed.

Author: pavoljuhas

setup.py

@@ -79,7 +79,7 @@ def getversioncfg():
     include_package_data = True,
     zip_safe = False,
     install_requires = [
-        'pycifrw',
+        'pycifrw != 4.3.0',
     ],
 
     author = 'Simon J.L. Billinge group',