'os' modules tmpdir function name fixed for 0.10.1 definitions.

node/node.d.ts

@@ -465,7 +465,7 @@ declare module "zlib" {
 }
 
 declare module "os" {
-    export function tmpDir(): string;
+    export function tmpdir(): string;
     export function hostname(): string;
     export function type(): string;
     export function platform(): string;