Fix IDEA IC support (fixes #507)

This fixes #507
I don't like it but it does its job.
Maybe if JetBrains will reply we'll have a better solution for it.

I've based this on master but if you want me to base it on old ``` fix-0.9.15 ``` branch let me know.
If we release from master right now it shouldn't be a problem but it's up to you if you want to release ``` 0.9.15.3 ``` like this or not.

Please see https://www.dropbox.com/sh/kzcmavr2cmqqdqw/uZPqwKMS6m/515-google-go-language.jar as a reference build.

Thanks.