This commit improves support of the Resource Handling features
introduced in Spring Framework 4.1. Those features add new ways to
resolve and transform static resources in applications.
See [this blog
post](https://spring.io/blog/2014/07/24/spring-framework-4-1-handling-static-web-resources)
for more details.

The `ResourceUrlEncodinFilter` is added for compatible template engines:
Velocity and Thymeleaf. It assists them with rewriting the URLs of
static resources when rendering templates.

New keys are added in the `ResourceProperties` in order to configure
the Resource Handling chain. `ResourceResolvers` and
`ResourceTransformers` are registered accordingly in
`WebMvcAutoConfiguration`.

Here is an example of enabling a `ContentVersionStrategy` on all
static resources, meaning their names will be changed for cache
busting purposes by adding a content hash at the end of the file name.
Like "/js/jquery.js -> /js/jquery-872ca6a9fdda9e2c1516a84cff5c3bc6.js".

```
spring.resources.chain.enabled:true
spring.resources.chain.strategy.content.enabled:true
spring.resources.chain.strategy.content.paths:/**
```

Closes gh-1604
Closes gh-3123