Update to use own package of google-diff-match-patch to solve encodeURI exception issue

Author: jackycute

package.json

@@ -14,7 +14,7 @@
     "connect-session-sequelize": "^3.0.0",
     "cookie": "0.3.1",
     "cookie-parser": "1.4.3",
-    "diff-match-patch": "^1.0.0",
+    "diff-match-patch": "git+https://github.com/hackmdio/diff-match-patch.git",
     "ejs": "^2.4.2",
     "emojify.js": "^1.1.0",
     "express": ">=4.13",