Doctest fixes for v0.2rc

This addresses most of the issues raised directly in https://github.com/astropy/astroquery/issues/384, but is not a PR on that issue.

I've gone through with a hack doctest (`make_doctests.py`) and tested all of the extracted code from the .rst docs.  I have *not* tested the docstrings!

(this PR mixes in some actual code fixes that I could separate into other PRs for cleanliness, but it's too much effort atm)

@cdeil
No, I guess we could create one.  The object in question is the `TableList`: https://github.com/astropy/astroquery/blob/master/astroquery/utils/commons.py#L232

It is the wrapper for when you have some set of tables.  It allows you to index by number or by name.  I like that functionality, but it is nonstandard.