Reorganize config files

Move all .codemate and .codemate_libroots into ~/.codemate as config
and lib roots. In future, all CodeMate run time stuffs will be in
~/.codemate.
Add SSH tunnel functions

During the daily coding, we need to login remote host which may be behind
the firewall or gateway. So I add SSH tunnel functions:

codemate create gateway
codemate create tunnel
codemate list tunnels
codemate connect tunnels
codemate list connections
codemate kill connection