Tests: Add helper functions for printing status and banner

Tests: Add helper functions for printing status and banner

Add three new printing functions:

print_ok: Print the OK status with optional color support.
print_fail: Print the FAIL status with optional color support.
print_test_banner: Print a test banner of the test description.

e.g.:
	sometest.sh:
	TEST_DESC="A really useful test"
	[...]
	source $TESTDIR/utils.sh
	print_test_banner $TEST_DESC
	[...]
	print_ok
	print_fail
	[...]

	$ ./sometest.sh
	----------------------
	A really useful test
	----------------------
	OK
	FAIL

Signed-off-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>