Changed every memcpy to SCA equivalent mbedtls_platform_memcpy

This makes physical attacks more difficult.
diff --git a/library/ssl_ticket.c b/library/ssl_ticket.c
index 7f20234..98147b7 100644
--- a/library/ssl_ticket.c
+++ b/library/ssl_ticket.c
@@ -208,7 +208,7 @@
 
     *ticket_lifetime = ctx->ticket_lifetime;
 
-    memcpy( key_name, key->name, 4 );
+    mbedtls_platform_memcpy( key_name, key->name, 4 );
 
     if( ( ret = ctx->f_rng( ctx->p_rng, iv, 12 ) ) != 0 )
         goto cleanup;