parse ASA and FWSM messages
always use mapped context if available
more reliably extract context names.

use "show context detail" rather than show context. The parsing is much
more consistent than trying to parse 'show context' output. On an ASA,
some of the columns of the 'show context' wrapped, making things dirty.
Allow monitoring multiple ASA/FWSMs in multiple context mode.

- FWSMChangePublisher is now SyslogListener
- SyslogListener publishes events based on an IP => device map (i.e. the
    source IP of the log)
- Multiple instances of FWSM/FWSMDumper/FWSMConfigManager etc are
  created to facilitate monitoring multiple devices.

This is somewhat of a WIP
update README