Jstenhouse/updating install path

Sidekick: @lars2893 
FYI: @prometheanfire

Updating default install path to `/opt/newrelic` since there are downloaded resources (tars) for each plugin and leaving them in `/opt` may not be desirable. Updating readme. Making the f5 plugin be in line with the others for install and plugin paths. Fixing an ohai warning for duplicate resource name.