Bug 907890 - show gecko make commands when using showcommands target r=mwu

(cherry picked from commit d61daef8fca7d6f335f659a8967bad423770e634)
Merge pull request #183 from lissyx/bug1047350

Bug 1047350 - Expose SDK version, needed to generate proper Edify scripts r=gsvelto
Bug 1059992 - be less verbose about non-gecko build output r=dhylands