Add FORCE_COLOR=1 to default environment variables

[Alhadis]

To cut a long story short, Mocha's coloured output is causing Emacs users grief because Emac's default compile command chokes on ANSI escape sequences when emitted from make -k feedback. @plroebuck identified the crux of the problem in chalk/supports-color handling of TERM=dumb environments.

I submitted a pull-request which fixes this, and simultaneously fixes compiler-mode's problems whilst affecting the coloured output of mocha.el:

Basically, the fix is to add FORCE_COLOR=1 in the environment, which is picked up by the supports-color module as a user's wish to go and use coloured output anyway, irrespective o f the TERM=dumb variable being set in both compiler-modes.

We can merge this now, it won't get noticed because the package's highlighting is currently working fine. But users will notice once chalk/supports-color#89 gets merged and shipped in a new release; having this the default for mocha-environment-variables ensures there's absolutely no friction when it does. =)

[plroebuck]

The "supports-color" PR for TERM=dumb does the same thing as FORCE_COLOR="0" would.
Wouldn't this technically be undoing the effect of chalk/supports-color#89 (when implemented)?

[Alhadis]

Nope. :=) Like I said in another thread, @scottaj gets it right because the escapes are going where they have to. But the command that was screwing it up was launching an extra shell per process, which means the ANSI escapes were interpreted literally by their dumb terminals before being piped through to the top-level process layer or something....

[Alhadis]

So we're not undoing anything because we're giving his application a chance to force colours even if the TERM=dumb was already being set in his environment each time.

[Alhadis]

Nudging @scottaj for review.

[Alhadis]

@scottaj Err... little help?