Removed the Spring3 extra
The controller previously used is replacement of the filter can't be used any longer.
Major changes brought to almost all classes
 * Assets has been replaced by AssetQuery and has the same purpose: build and perform queries against the asset graph. However, now the assets are all stored in cache before being filtering by the query.
 * All configuration points have been moved to a new Context class, which is the new entry point for all configurations. All classes have been updated to access the context. The context is initialized at startup, by the filter. All *system.java have been removed.
 * Updated AssetUtils utilities to filter Asset and no AssetStorageUnit any longer.
 * The HashMapAssetCache (previously based on a simple Hashmap) has been replaced by a LRU cache. This will prevent memory issues in particular contexts. See dandelion/dandelion-datatables#238
 * The AssetServlet now applies some HTTP headers on all served assets. The headers change depending on the DevMode.
 * All configuration points are now grouped together in the DandelionConfig enum.
 * The ConfigurationLoader and StandardConfigurationLoader have been updated: they no longer need to load a default configuration. All default configurations are stored in the DandelionConfig enum
 * Fixed issue with displayed asset in the GraphViewer
 * Fixed issue with bundle name (configured with the AssetRequestContext) that contained white spaces
 * Fixed issue with the WebJarLocator: it now requires caching
 * Updated all unit tests
Renamed configuration and improved asset exclusion mechanism
Renamed minification.enabled to minification.on
Assets can now be excluded by name and by type. This eases the way bundles are built, since we don't need to differentiate a JS and a CSS with its name.
All web-related constants are now gathered in one place
Also renamed some method of Configuration for a better consistency