[UP-4274] OSX focus stealing

https://issues.jasig.org/browse/UP-4274
The problem is the SASS plugin.  I could not find a way to tell the SASS plugin to run headless.   I spent a bit of time trying to hack a workaround into the SASS plugin itself, but was never able to get it to work correctly.    It's *possible* that leaving this out completely would be fine if you are using deploy-war since it passes the headless flag to the mvn build, but if you run "mvn install" by hand it's  still gonna steal focus without this plugin.

A workaround for that would be just to have OSX users set the env variable "JAVA_TOOL_OPTIONS=-Djava.awt.headless=true", but I was concerned about the consequences if you are trying to run other java apps.

If someone else is aware of a better option, I would love to hear about it though because I agree with Andrew that this is not ideal.