ErrorProne has false positives in non-java builds

[henriquetruta]

ErrorProne parser is showing up some false positives in logs that aren't even from java builds, like in this scala log: https://gist.github.com/henriquetruta/00f851e1a88e371140d7be337eaecd2d
it picked up an error with startLine/endLine 6

It also generated 3 violations on this other scala build: https://gist.github.com/henriquetruta/d6e46355539609415ab8ad738192a46e

[tomasbjerre]

There is also: #37

Probably best to wait for this one to get merged: google/error-prone#1132 and then rewrite the parser to parse that output.