green: Remove the dependence on the crate map

This is the final nail in the coffin for the crate map. The `start` function for
libgreen now has a new added parameter which is the event loop factory instead
of inferring it from the crate map. The two current valid values for this
parameter are `green::basic::event_loop` and `rustuv::event_loop`.

src/libstd/lib.rs

@@ -84,7 +84,7 @@
 //        '__test' module.
 #[cfg(test)] #[start]
 fn start(argc: int, argv: **u8) -> int {
-    green::start(argc, argv, __test::main)
+    green::start(argc, argv, rustuv::event_loop, __test::main)
 }
 
 pub mod macros;