Use select2 to choose read and write

I created new branches and Pull Requests for all 4 of the issues covered in the initial Pull request #14. These only contain the related changes.

I also updated the solution to also support creating new workflows and I did some minor optimization mainly to improve the readability of the code.

Added a new PR with only changes needed for this issue. Pull Request #17

https://bitbucket.org/eactive/integrated-workflow-bundle/pull-requests/17/integrated-506-use-select2-for-permissions/diff

Reviewer is Marijn

@Roy Frans Maybe it is better to start a new project (http://integratedfordevelopers.com/content/documentation/article/getting-started-with-integrated). You can start a new branch and copy the code you need manually.

I can't seem to get the original project back to work after upgrading to win 10;
I did succeed in getting another project to work with the solution from Pull Request #14, but after the initial load for some reason javascript stops working without giving an error.
I tried to replace some event handlers with delegated event handlers to no longer require the javascript inside of form_div_layout.html.twig but didn't got it to work due to the above problem.

@Roy Frans can you please create an issue branche for this issue only and add only the changes for this issue here. It is very hard to review when different issues are combined in a pull request.

Also please don't commit the select2.js. This one is already available and in the default Integrated installation (https://bitbucket.org/eactive/integrated/src/d4410350221699c214409a6b0f75830b20425684/app/config/config.yml?at=master&fileviewer=file-view-default#config.yml-58).