Updated for symfony 2.5 + features

There's a lot going on in this PR, here are a couple of things...
- Updated for Symfony 2.5, including merging one of the existing branches for 2.2
- Updated to the non beta version of spec, fixed specs accordingly
- Nested object schema generation
- Switched to annotation_reader included with symfony
- Support for entity type's from the form guesser
- Fixed property handler sorting so that annotations can override the form guesser, etc.
- Added several other annotations, format, options, etc. to expand the functionality offered by JSON Schema
- Added ability to ignore properties from being included in the JSON Schema
- Added default titling

There are probably some other things I am missing, but in general I tried to stick with the spirit of what was originally done here.  I am currently using this in a project pretty heavily and have a vested interest in continued development of the project, specifically I'd like to add some better functional tests (phpunit) if that's palatable. I'd also like to add support for definitions, as well as metadata using the JMS Metadata package so that yaml and xml would be supported.

Feedback welcome, thanks!
ha, the spec says it should be `application/json` or any of its subtype (f.e `vnd.something+json`; `+json` being important here).

It's optionally followed by a `profile="<link-to-schema>"`, OR a  `Link` header (= the one we implemented).

It means the content-type should be related to the content of the response, which can be anything, literrally (but most of the time `application/json`, sadly). 
Anyway, let's keep it like that :)