Continuous Release: remove 'dev'?

The continuous release process was established in #1124, but it doesn't fully "work" yet because we're pushing .dev releases to pypi, which means that `pip install astroquery` doesn't install the latest version of astroquery.

So, what is the appropriate way to make this a fully automated release process? Can we just drop the 'dev' from the version name? Does that break some of the astropy-helpers machinery?

cc @eteq, @bsipocz

Review the continuous release process established in #1124 and the astropy-helpers machinery mentioned in the issue. Determine whether removing “dev” would make pip install astroquery select the latest release without breaking that machinery, and document the appropriate fully automated release behavior as done.

Written by the indexing model from the issue text.