More helpful error logging when failing to load reaction library.

Might not make a difference if you could see the logging.info call two lines earlier,
but when running unit tests (databaseTest) that is not necessarily the case.

rmgpy/data/kinetics/database.py

@@ -248,7 +248,11 @@ def loadLibraries(self, path, libraries=None):
                         label=os.path.dirname(library_file)[len(path)+1:]
                         logging.info('Loading kinetics library {0} from {1}...'.format(label, library_file))
                         library = KineticsLibrary(label=label)
-                        library.load(library_file, self.local_context, self.global_context)
+                        try:
+                            library.load(library_file, self.local_context, self.global_context)
+                        except:
+                            logging.error("Problem loading reaction library {0!r}".format(library_file))
+                            raise
                         self.libraries[library.label] = library
                         self.libraryOrder.append((library.label,'Reaction Library'))