SConstruct : use `universal_newlines` instead of `.decode()`
SConstruct : use `universal_newlines` instead of `.decode()`

- `universal_newlines` offers better handling of encoding, and a clearer path to using the `text` argument when Python 2 support is dropped.

hradec/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,hradec/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,hradec/gaffer