Supress colour output if not terminal

We ran into a problem that some log aggregating services don't deal with (ie, don't strip) ANSI escape sequences resulting in quite an amount of gibberish obscuring the output. This was particularly a problem with AWS CloudWatch, so much so that we (admittedly reluctantly) have done the usual trick of detecting whether the stdout handle is a terminal and deciding whether to colour or not based on that.

Thanks to @Imogi for his help while preparing the patch that enabled this improvement!

What's Changed

• Only colour log output if attached to a terminal by @istathar in #107

Full Changelog: core-program-0.4.5.0...core-program-0.4.5.1