Revert "Update version to 1.7"

This reverts commit 6fbf4494b5.

src/compiler/program.ts

@@ -12,7 +12,7 @@ namespace ts {
     
     let emptyArray: any[] = [];
     
-    export const version = "1.7.0";
+    export const version = "1.6.0";
 
     export function findConfigFile(searchPath: string): string {
         let fileName = "tsconfig.json";