CLN/BUG/ENH: Raise AttributeError with pd.options

It's called OptionError now and it subclasses both AttributeError (for
hasattr) and KeyError (for backwards compatibility). Hurray!
Merge pull request #5188 from jtratner/fix-hasattr-on-options-object

CLN/BUG/ENH: Raise AttributeError with pd.options