[FIX] Object action in show builder is now optional

Twig was complaining about undefined variable object_actions in case
key of missing key
Edit builder supports object actions

Also edit builder supports object actions. Now, delete and show actions
can be used in edit builder. (See related: #330)
Support to call php code on any form option

Adds support to call custom php code on any form option.
The code which should be executed has to be wrapped with __php(<<php code>>).

Example usage:
...
addFormOptions:
    languages: __php($this->getLanguages())
    type: __php(new \Foo\Bar\BazType)
    ...
Made selector non-greedy
Sanity checks to prevent errors when no data was submitted (UploadType and SingleUploadType)
Doc update on Submitting issues
Add margin between single-upload field and it's error message
Add Propel support for EntityPicker (untested, TODO: test!)
Move doctrine-dependadnt form type services to doctrine.xml
Add exception when no model manager was selected
Load only one services configuration
Rename services
Small styles fix
[FIX] Show template generation : no error if object_action is not defined in generator.yml
[FIX] object_actions is now optionnal
Merge pull request #347 from sescandell/master

Let's "object_actions" optionnal in show templates/actions
Cancel sortable on textarea and select tags
Remove suggestion for knp-markdown-bundle (local viewing of docs not yet avaliable)
Fixing bad type name for PropelEntityPickerType.php
Import dashboard routes added to DOCS
Merge pull request #339 from kufi/patch-4

Support to call php code on any form option
Refactor form services:

* move model-manager specific forms into seperate directories
* rename services (add model-manager prefix)
* change service aliases

Fixes for SingleUpload widget:

* load thumbnailgenerator from bundle config
* use specified thumbnail filter to generate thumbnails
Refactor services fix