abstract the page layout into “layout.tag”

abstract the page layout into “layout.tag”

RSS is becoming outdated, JSon is a better example

 * The old datatables-servlet2 dependency has been removed from the pom.xml
 * Some attributes have been renamed (e.g. paginate => pageable)
 * Starting from the v0.10.0, all web components (servlet, filter) must be explicitely declared in the web.xml file. That's why I added the following declaration: DandelionFilter, DandelionServlet and DatatablesFilter
 * Added a new datatables.properties file in order to disable the asset management brought by Dandelion-Core. This is equivalent to the old cdn=true table attribute

New dependencies added
Old tables replaced by Datatables using Dandelion-Datatables

- commented out all Spring MVC config related to content negociation so
the app works well in HTML for now
- Integrated Bootsrap look&Feel in the 'vets' section

SPR-6448
+ commit the gross of the files
+ added maven pom