Switch to ant updateMetaXml

Previously, we used a Python script for a few different editing operations which are no longer needed with this branch.  The only functionality from the script still relevant to the project was the updating of meta.xml files to the correct version.  This branch moves that functionality into the build.xml file so it can be run by ant instead of Python.

When changing the version of a managed package Cumulus depends on, edit the version.properties file in the root of the repository then run `ant updateMetaXml` from the root of your local repository to update the files.

Fixes #215