make scaladoc handle linking to external javadoc or scaladoc properly

[tbarker9comcast]

Could not get the scaladoc parameter -doc-external-doc to work properly. As of creating this issue, this affects PaxosSupervisor and SiriusConfiguration. To see the linking warnings, run sbt doc at the root of the project.

[andrewdbate]

I came across this issue when trying to find a solution to a similar problem. I eventually found a solution for linking to external Javadoc, and posted an answer on Stack Overflow here. Perhaps you'd find it useful. It saves you from hard coding the strings of the Java classes into the documentation.

[tbarker9comcast]

Thanks! Will check it out