0.50.1 Release

**STOP** First merge #245 first, which contains documentation updates, if you have not done so already.

This is the pull request to make 0.50.1 the master. This release does a few things:

  # Adds support for replacement documents to permit update/delete.
  # Moves much of the critical documentation into the source tree so that documentation can be tracked with the code release.
  # Changes to Slice which reduces some functionality to improve performance and reduce index size.
  # Fixes miscellaneous problems with authenticated distribution.
  # Misc other bug fixes.