add urlEncode function

[shekhargulati]

[engfragui]

@shekhargulati Would you want an implementation of urlEncode() without using any external library like URLEncoder, right?

[arcticicestudio]

I generally think this method would be superfluous, as mentioned by @engfragui the JDK already provides the URLEncoder class which is backwards compatible from Java 8 down to Java 5. Currently can't think of any use cases a additional implementation would be necessary.