Adds verbose mode to the test suites

Added a verbose option to the generated test suites which can list the
dependencies not met for skipped test cases.
Also clarifies internal interfaces between the main_test.function and test code,
and fixed a bug on calculating available tests in run-test-suites.pl.
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index fb77e15..58f827c 100755
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -2,6 +2,8 @@
 
 # run-test-suites.pl
 #
+# This file is part of mbed TLS (https://tls.mbed.org)
+#
 # Copyright (c) 2015-2016, ARM Limited, All Rights Reserved
 #
 # Purpose
@@ -66,7 +68,8 @@
         print "(test cases passed:", $suite_cases_passed,
                 " failed:", $suite_cases_failed,
                 " skipped:", $suite_cases_skipped,
-                " of total:", ( $suite_cases_passed + $suite_cases_failed ),
+                " of total:", ($suite_cases_passed + $suite_cases_failed +
+                               $suite_cases_skipped),
                 ")\n"
     }