3.1.0

- Closes #183. Addresses some issues with using the example in strict mode.
- Closes #231. Replaces Buffer() with Buffer.from().
- Closes #233. Uses underscore in a manner more compatible with TypeScript.
- Closes #238. Replaces body-parser with urlencoded() for express >=4.
- Adds maintenance notice.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "saml2-js",
-  "version": "3.0.1",
+  "version": "3.1.0",
   "description": "SAML 2.0 node helpers",
   "author": "Clever",
   "license": "Apache-2.0",