Don't alias __typename

[aaronwhite]

This fixes issue #120 by selectively modifying the alias function to not alias __typename. There may be a better way to tackle the issue, but this works in my case as is.

[dillonkearns]

Thank you Aaron!

I moved the logic for skipping the alias for __typename into the maybeAliasHash since that's where the other logic lives for deciding whether or not to use an alias.

I also changed it to return Nothing instead of Just "__typename" so that it uses no alias instead of an alias like __typename: __typename.

I think it's good to go now!

[aaronwhite]

Makes sense & thank you for cleaning it up!