Revert "attempt to run RMG without thermolibrary"

Doesn't work.
This reverts commit 384db4e.

Author: keceli

rmgpy/data/thermo.py

@@ -734,8 +734,6 @@ def getThermoDataFromLibrary(self, species, library):
         
         Returns a tuple: (ThermoData, library, entry)  or None.
         """
-        if library is None:
-            return None
         for label, entry in library.entries.iteritems():
             for molecule in species.molecule:
                 if molecule.isIsomorphic(entry.item) and entry.data is not None: