Issue #8, '--sample' flag for 'show' command.

Allows to specifiy samling frequency when returning the observations (so
that if there is a whole bunch of observations but you want a more
synthetic view, you can do that).
Updated license info.

Included link to the project on github, added license info to files
where missing.
Issue #7, --data argument.

Allows to specify a different source of data by naming file path
(including /dev/stdin).