WIP: Ignore 400 errors on index creation

Those warnings were scary. :smiling_imp: 

So...this is incomplete because:
 - it only got rid of one PUT warning--I'm not sure where the other 2 (for me) are coming from (@aron mentioned threading?)
 - it MAY be OK to remove the `InvalidIndexNameException`, but I've been unable to find if that also throws a 400--but I'd expect it too. I left it there just in case.

Thoughts welcome!