Add onewire parser

Add onewire parser

This parser will parse data from onewire server. It will use the
network protocol to query the data, thus it is capable of fetching the
data over any network location supported by the ownet library.

The first parser_data string must containt the server address:ip. The
rest of the strings are used to query data entries from the server. If
one wishes to leave blank entries to some of the data, a "U" string is
passed as is to the rrd_data.

Signed-off-by: Timo Kokkonen <timo.t.kokkonen@iki.fi>