* Add in support for looking for substring in response
* Add note to CHANGELOG.md
* Switch from substring match to regex match
* Requested code changes
* Make requested changes and refactor to avoid nested if-else.
* Convert tabs to space and compile regex once
Also changing the net_response and http_response plugins to only accept
duration strings for their timeout parameters. This is a breaking config
file change.
closes#1214
Frederick Roth
Daniel Nelson
Patrick Hemmer
Len Smith
Cameron Sparr
Luke Swithenbank