[sup] Use a consistent clap features set.
[sup] Use a consistent clap features set.

This change updates the feature set for the Supervisor's clap crate to
include `"stable"`. All other Habitat clap-depenent crates use the same
feature set (suggestions, color, and unstable) which led to crates being
recompiled more often than necessary (churning on differing clap
builds).

Signed-off-by: Fletcher Nichol <77a0fd9e8048bbacd11af4e957bc6ff03b549f49@nichol.ca>

nathenharvey/habitat,georgemarshall/habitat,georgemarshall/habitat,rsertelon/habitat,rsertelon/habitat,nathenharvey/habitat,habitat-sh/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,georgemarshall/habitat,rsertelon/habitat,georgemarshall/habitat,georgemarshall/habitat,georgemarshall/habitat,nathenharvey/habitat,habitat-sh/habitat,nathenharvey/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat,nathenharvey/habitat,habitat-sh/habitat,habitat-sh/habitat,georgemarshall/habitat,georgemarshall/habitat,habitat-sh/habitat,nathenharvey/habitat