Change release checking from SourceForge to GitHub

[mstovenour]

MisterHouse has a user code file, mh_release.pl, that checks for very specific text in the SourceForge documentation download.html page. This script will notify a MisterHouse user of a new update once the docs/download.pod/.html file is modified on SourceForge.

This enhancement request would modify mh_release.pl to use the json interface on GitHub to check the MisterHouse release tags looking for a newer tag. Once this feature is implemented the docs/download.pod file can be modified to simply point at the GitHub releases page.

[mstovenour]

Design note: Modify the version check to look for the "first" (i.e. top most) tag that matches the pattern /v\d+.\d+/.  That should cover us if someone creates a tag for a different use.