Added bundles dependencies
Added bundles dependencies

* Each bundle with dependencies implements DependentBundleInterface
* Each bundle returns its dependencies (non-testing)
* Fixed all tests to work with new dependency engine
* Because all dependencies are resolved on running time, tests have been simplified. Even if a bundle has a dependency with another bundle,
and this bundle changes its dependencies, any test will need changes.
* Removed dependency with BambooBundle in tests
* Added default value in `elcodi_config` expression language function.

elcodi/SitemapBundle