Add check-netstat-tcp.rb, heavily based on metrics-netstat-tcp.rb
opsgenie heartbeat: use apiKey and (new!) source config
consistently use '...'
check-netstat-tcp.rb fixes since it's a check not a metric
Windows disk usage metric
adding gluster/gluster-georepl-status.rb

- plugin to check if Gluster's geo-replication is healthy or not.
added flag to pass states
bugfix: requires sudo
removing 1 from list of watchers is flawed, the check does not watch the tube it is checking
renamed check and made it executable
added more exclusions
Add check ssl expiry
Fix message
fix syntax to fix test
fix json syntax in plugin example configs
add ipv6 support to check-netstat-tcp.rb
Change message format handed to Logstash.

Matches https://logstash.jira.com/browse/LOGSTASH-675
ssl support
url-escape the 'target' parameter to avoid 'URI::InvalidURIError: bad URI(is not URI?)'.
add imkayac notification.