Siena support for Play! Framework v2.x

The siena module automatically enables Siena support for your application for GAE/MySQL/PostgreSQL/H2 databases.

Release notes

v2.0.6 provides support for :
- GAE
- MySQL
- Postgresql
- H2
- GoogleCloudSQL
- Amazon SDB
v2.x brings support for IDs of type Long (auto-generated or manual) and String (manual or auto-generated as UUID).
v2.x brings a new class called EnhancedModel which is a normal siena.Model enhanced at runtime by Play to provide all() function (and other functions also but it will be detailed later). Please see below for more details.
v2.x is a complete refactoring of siena module based on Siena v1.x. Yet, for those who used Siena before, it doesn't change anything as Siena v1.0.0 is 100% backward compatible (at least in theory).
v2.x is compatible with Play version >1.2.1 and uses dependency management.

Note v1.x only supported GAE but this is not the case anymore. Other NoSQL Databases will be added later.