tests: change info messages from yellow/brown to cyan

tests: change info messages from yellow/brown to cyan

Now that we've adopted a "traffic lights" coloring scheme, yellow is
used for warning messages, so we need to re-color info messages to
something less alarmist.  Blue is a universal color for informational
messages; however we are using that for skipped tests in order to
align with the color schemes of other test suites.  Therefore we use
cyan which is also blue-ish, but visually distinct from blue.

This was suggested on the list a while ago and no-one raised any
objections:

    http://thread.gmane.org/gmane.comp.version-control.git/205675/focus=205966

An earlier iteration of this patch used bold cyan, but the point of
this change is to make them less alarming; let's drop the boldness.

Also paint the message to report skipping the whole thing via
GIT_SKIP_TESTS mechanism in the same color as the "info" color
that is used on the final summary line for the entire script.

Signed-off-by: Adam Spiers <git@adamspiers.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>