Allowing for phpunit test to warn about need install first

Phpunit tests cannot run if Mahara is not installed but doesn't give
any warning to this fact

Change-Id: Ie8aecf35fef730adbb42856da13ff712ed8505d5
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

htdocs/init.php

@@ -439,6 +439,9 @@ if ($siteclosed && !$USER->admin) {
 // check to see if we're installed...
 if (!get_config('installed')) {
     ensure_install_sanity();
+    if (defined('TESTSRUNNING')) {
+        die("Need to have Mahara installed before phpunit tests will run. Please install via 'php htdocs/admin/cli/install.php'");
+    }
 
     $scriptfilename = str_replace('\\', '/', $_SERVER['SCRIPT_FILENAME']);
     if (!defined('CLI')