Added structure cache warmer
Started refactoring for Snippets

- Make Structure a super type
- "Page" will take role of current Structure
- Snippet will be subclass of Structure
Introduced Page and added ContentMapperRequest object

- Introduced Page object as subtype of Structure.
- Added ContentMapperRequest and saveRequest method to content mapper
INtroducing Structure support
Added page and snippet mixins
Added Sulu Fixtures

- Loads data for webspace pages and snippets using the content mapper
Do not overwrite configured webspace path
Validate content mapper request
Throw better exception when no structure directory present
Added snippet support to loadByNode
Added TODO to content mapper test
fixed content mapper and session manager interface
fixed structure and session manager
Added support for saving snippets to template dirs
Fixed tests
Merge branch 'feature/page-refactor' of git://github.com/sulu-cmf/sulu into feature/page-refactor
removed deprecated and add new parameter
fixed constants
added dev stability
added node state to snippet