Change from "classic" TS 1.6 imports to the default resolution scheme.

- Use relative imports in place of most of our absolute ones.
- Add "private" ambient modules for modules that we need to import using
an absolute path (e.g. when app/.../test-something.ts needs to import
ui/styling/style-scope)

ui/image-cache/image-cache.android.ts

@@ -1,4 +1,4 @@
-import common = require("ui/image-cache/image-cache-common");
+import common = require("./image-cache-common");
 
 class LruBitmapCache extends android.util.LruCache<string, android.graphics.Bitmap> {
     constructor(cacheSize: number) {
@@ -62,4 +62,4 @@ export class Cache extends common.Cache {
     public clear() {
         this._cache.evictAll();
     }
-}
+}

ui/image-cache/image-cache.ios.ts

@@ -1,4 +1,4 @@
-import common = require("ui/image-cache/image-cache-common");
+import common = require("./image-cache-common");
 import httpRequest = require("http/http-request");
 import utils = require("utils/utils");
 import trace = require("trace");
@@ -89,4 +89,4 @@ export class Cache extends common.Cache {
         this._cache.removeAllObjects();
         utils.GC();
     }
-}
+}