Fixed reference to README in package.json

Author: palemieux

package.json

@@ -6,7 +6,7 @@
     "homepage" : "https://github.com/sandflow/imscJS",
     "bugs" : "https://github.com/sandflow/imscJS/issues",
     "repository" : "github:sandflow/imscJS",
-    "files" : ["src/main/js", "README.md"],
+    "files" : ["src/main/js", "README.txt"],
     "keywords" : ["imsc1", "ttml", "imsc"],
     "author" : "Pierre-Anthony Lemieux <[email protected]>", 
     "main" : "src/main/js/main.js",