added infrastructure for go scripts

Signed-off-by: Andrei Thorp <athorp@evernote.com>
Refactoring bump-mac-subrepo to not use panic

Signed-off-by: Andrei Thorp <athorp@evernote.com>
Added colour to bump-mac-subrepo

Signed-off-by: Andrei Thorp <athorp@evernote.com>
switched to using go-sh instead of exec

Signed-off-by: Andrei Thorp <athorp@evernote.com>
Removed redundant check in bump-mac-subrepo

Signed-off-by: Andrei Thorp <athorp@evernote.com>