Updated package.json to reflect the renaming of MusicSheetAPI

package.json

@@ -2,8 +2,8 @@
   "name": "opensheetmusicdisplay",
   "version": "0.0.1-alpha.0",
   "description": "An open source JavaScript engine for displaying MusicXML based on VexFlow.",
-  "main": "dist/src/MusicSheetApi.js",
-  "typings": "dist/src/MusicSheetApi",
+  "main": "dist/src/OSMD/OSMD.js",
+  "typings": "dist/src/OSMD/OSMD",
   "scripts": {
     "test": "grunt npmtest",
     "postinstall": "typings install",