[fix] golang 1.6 imports

[WnP]

Fix those errors on golang 1.6:

cannot find package "golang.org/x/tools/go/gcimporter" in any of:
…

here you can found more information about gcimporter and

no buildable Go source files in /home/scl/go/src/golang.org/x/tools/go/types

as go/types is now part of golang sources

[clipperhouse]

Thank you!