Removed old log4j.properties from remote poller NSIS installer. Updated
embedded log4j2.xml config so that the console output is cleaner and also
added a log4j2.xml config to the NSIS installer so that logs will be printed
to the /Program Files/OpenNMS Remote Poller/logs directory in addition to
stdout console logging. Reworked the format of the network settings panel in
the NSIS installer. Changed version check to only allow installation on
Windows Vista or higher and removed some Java6-specific sections since we
now support only Java7.