Update cowlib to 0.6.0

Adds chunked transfer-encoding support plus a few functions imported
from Cowboy. Also adds a function to build requests for clients.

src/cowlib.app.src

@@ -14,7 +14,7 @@
 
 {application, cowlib, [
 	{description, "Support library for manipulating Web protocols."},
-	{vsn, "0.5.1"},
+	{vsn, "0.6.0"},
 	{modules, []},
 	{registered, []},
 	{applications, [