v0.2

This is the second release of nixos-scripts.

Highlights are the new "channel" subcommand, as well as the "switch"
command changes.

Changes:

    * "channel" command:
        * Channel command utility added
        * Utilities were partly re-written for the "channel" subcommand
        * Command for showing channel generations added
        * Command for diffing channel generations added
        * Command for checking out channel generations added

    * "switch" command:
        * Hostname is included by default
        * Note that "switch" is default action for this command
        * Do not annotate tags as default
        * Flag for doing all the things, but not nixos-rebuild

    * "update-package-def" command:
        * Option for not checking out the base branch added

    * configuration file support
        * example RC-file
        * Use variables from config file whenever possible

    * less output for normal users (-v flag)
    * more debugging output (-d flag)