Enable third party contributions

- Add instructions for contributing to ARM Trusted Firmware.

- Update copyright text in all files to acknowledge contributors.

Change-Id: I9311aac81b00c6c167d2f8c889aea403b84450e5
diff --git a/lib/non-semihosting/strlen.c b/lib/non-semihosting/strlen.c
index 5c1e7a6..a388fe4 100644
--- a/lib/non-semihosting/strlen.c
+++ b/lib/non-semihosting/strlen.c
@@ -28,9 +28,7 @@
  */
 
 /*
- * Portions copyright (c) 2009-2013, ARM Ltd. All rights reserved.
- * ---------------------------------------------------------------
- * File: lib/strlen.c
+ * Portions copyright (c) 2009-2013, ARM Limited and Contributors. All rights reserved.
  */
 
 #include <stddef.h>