[WIP] Doctrine integration

I'm integrating Doctrine in Fork. I'll keep a checklist here containing my progress. Every help is welcome.

## Modules

- [ ] Analytics module
- [ ] Blog module
- [x] Content Blocks module
- [ ] Extensions module
- [ ] Faq module
- [ ] FormBuilder module
- [ ] Groups module
- [ ] Locale module
- [ ] Location module (@MathiasDewelde is working on this module)
- [ ] Mailmotor module
- [ ] Pages module
- [ ] Profiles module
- [ ] Search module
- [ ] Settings module
- [ ] Tags module
- [ ] Users module

## Core

- [ ] emails
- [ ] meta
- [ ] modules
- [ ] modules settings
- [ ] modules tags => Why isn't this located in the tags module?
- [ ] timezones
- [ ] groups
- [ ] rights
- [ ] backend navigation
- [ ] hooks (queue and subscriptions)