Merge pull request #3 from rstoyanchev/master

Add CachingResourceResolver
basic support for Groovy Templates

Requires Groovy >= 2.3.0
See Markup Template Engine documentation:
http://beta.groovy-lang.org/docs/groovy-2.3.0/html/documentation/markup-template-engine.html
Add resource transformer integration

* transform resources links within CSS files using a CssLinkResourceTransformer
* add styles in CSS file (font and background image)
Update with latest Groovy templates support

Those changes are based on a private branch featuring the current work
on Groovy MarkupTemplate support in Spring Framework.
Update example app with changes from SPR-11781
Update app with latest refactorings

* upgrade to boot 1.1.1
* update with latest refactorings for SPR-11871
* try including a global helper for resolving resources URLs
Update documentation

* latest changes are in Spring Framework master
* document how to start the app
* add pointers to interesting classes
Support production version

* copy images in gulp build
* show both dev+prod run commands in README
reproduce template issue with Groovy Markup Templates
Fix Groovy Markup Template example

* use a Helper Function instead of wrapping it with a MethodClosure
Optimize images in Gulp build

* upgrade Node.js dependencies
* use gulp-imagemin to optimize images at build time
Fix markup error
Add HTML5 AppCache example

* Add first draft for AppCacheResourceTransformer implementation
* Add sample appcache manifest and example page
* update WebConfig with this new Transformer
Document AppCacheResourceTransformer
Add example with a LESS stylesheet

At dev time, this LESS stylesheet is transpiled on the client side
by the LESS JavaScript transpiler.

In production, the transpiled version of that stylesheet is used
(a new gulp task is added to transpile this during the build)
Upgrade Gradle to 1.12
Update dependencies

* Spring Boot
* Tomcat
* Groovy
Update application

* update to latest Spring MVC API in snapshot version
* simplify the projectroot configuration for resources
* show only relevant resource links in the LESS example template
Latest ResourceHandlerRegistry API update

This change greatly simplifies the configuration of resolvers and
transformers in the ResourceHandlerRegistry API.

See SPR-11982
Gradle version upgrade to 1.12