Support for multiple template repositories

A working first stab at support for multiple template repositories. Main aim is to allow for internal company repositories so that company specific templates needn't pollute the public repository.
just thinking, if we have other repo metadata (such as logo, description, whatever) maybe we want to bootstrap all of it from the url ... that is, the repo would have a .properties file (there already is one IIRC) and in that we'd put the name etc.