Support source.list for channel list.

[c9s]

When channe list growing, It's really hard to export channel list from one machine to another. there is no quick way to export/import channel list.

My idea is from Debian's sources.list, users can have many package sources (just like PEAR channel source), pyrus can use this source list to update / upgrade packages very easily.

But I think It's better to design another component to manipulate channel list data, and put channel list info under user's $HOME/.pyrus directory or something , may store in JSON format, so applications can manipulate these data very easily.

If pyrus can accept this, I am glad to design such component and provide a API , documentation to support Pyrus. :-)

[till]

@c9s I know it's late — but feel free to design it and come up with a PR.