[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
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
SingleUpload widget fix
Fixed bug introduced in some commit on double_list/doctrine_double_list
Merge pull request #349 from pataprout/master

Error 500 : Could not load type "doctrine_double_list"
Merge pull request #334 from eymengunay/feature-oa

Edit builder object actions support added
Prebind request was missing from new action template
Restructuring Generator/Actions, actions are organized into 3 categories now:

* Generic actions - do not require any parameter (eg. Save, List)
* Object actions - require Primary Key parameter (eg. Edit, Delete)
* Batch actions - require multiple Primary Key parameters (eg. Delete selected)

Also changed templates and builder logic for Edit, New and Show actions:
* `findActions()` method looks for a generic action by given name
* if no generic action is found, it looks for object action by given name

Which allows to mix generic and object actions (and control their order), for example:

```yaml
builder:
  edit:
    actions:
      save: ~
      show: ~
      list: ~
```

will be displayed as `[Save] [Show] [List]`  (notice mixed order: `[generic action] [object action] [generic action]`).
Merge pull request #350 from eymengunay/fix-prebind

Prebind request was missing from new action template
Changed batch translations key