Add basic docs for metadata caching.
Add docs for OrmCacheShell.
[fr] App class
[fr] Email Class + [en] notation array() to []
[fr] HttpClient Class + [en] Typo
array() to [] in Router
[fr] Security Class
[fr] Time Class + [en] array() to []
Fix grammar.
Move orm_cache shell docs to ORM section.
Merge pull request #1356 from cakephp/3.0-orm-cache-shell

3.0 orm cache shell