[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)
Reintroduce ShowBuilder to DoctrineGenerator - Fixes #338
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
Introduceing SingleUpload widget
Add missing file
Fix deletable notice
fix javascript error when previewImages is set to false
Merge pull request #340 from cykus/master

fix javascript error when previewImages is set to false
Added support for symfony 2.2
Update Resources/skeleton/bundle/generator.yml

Reverting changes from 458667bb15e10ac716d6aae63ca1b5d478e3f64c

The trailing double quote is necessary.
Fixed php syntax error: unexpected ')'
Merge pull request #342 from hectorh30/propel-nested_list-syntax-error

Fixed php syntax error: unexpected ')'
Update .travis.yml
Update .travis.yml
Update composer.json
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