Move docs/fits to docs/io/fits - #245

Okay. Should be fine.

@iguananaut - at the same time, could you reorder the front page of the io.fits docs according to the layout in #218, like @mdboom did in #219?

@iguananaut - will you be able to move docs/ascii to docs/io/ascii as well? If not I can do this.

Note that we may decide in #217 that the docs don't have to mirror the code structure, but I personally think it makes sense to try and mirror it as much as possible, so I think we should move fits, ascii, and vo to an io directory regardless of what happens in #217.

Sure, I can do that.

The only holdup right now is that I have a bunch of doc updates for pyfits that I need to merge into Astropy before I start moving things around. I figure it'll be easier that way.

Pretty much reorganized all the astropy.io.fits docs. This is a fairly significant reorg that I will probably want to backport to pyfits sooner rather than later.

I tried automodapi and the output was pretty acceptable. That said, I still prefer the existing organization of pyfits' API docs so I kept that as is.

Otherwise, I made docs/io/fits/index look more like the indexes of the other sub-packages' docs. This involved moving the old "tutorial" section into the "Getting Started" section, which worked out fine.

Barring any further comments I'll go ahead an merge this soon.

This looks fine to me for 0.1.

For 0.2 (or possibly later, because this isn't a big deal) @iguananaut , can you see about deciding what needs to be in automodapi to make it "perfect" for your use? But no rush.

Looks good - feel free to merge!