Plugin assets+url rewriting

Hope you like this somewhat bigger patch for the docs.
I built the docs on my machine but I was experiencing a strange behaviour in the sidebar tree. I've added a new file to installation and now links to this new file appear on at least two places where they shouldn't (and aren't)!

- Added note about handling plugin assets through Dispatcher is inefficient
- Moved url rewriting to a separate file
- Added a section about what if you can't use url rewriting
- Improved core config section about App.baseUrl
- Added section in deployment about improving performance due to symlinking
- Removed parts of the blog tutorial (duplicated content)