Update gpi_compiler for git instead of svn

[mperrin]

The build script for the pipeline runtime-compiled versions needs updating for Github instead of svn.

• [ ] Update list of excluded files from zips
• [ ] Remove obsolete code for ignoring no-longer-present directories for releases, tags, etc
• [ ] Replace svnonly with gitonly option to ignore files which are not committed to repository
• [ ] Update version string to use github SHA hash (or a short version of that) instead of svn id.