* Documents with a non null data reference are considered as 'documents
to edit'
* The generated widget for a document to edit is a container, containing
a link to download the previous revision, and a fileInput to update the
document
* AssertJ version has been upgraded from 1.7.0 to 3.11.1, in order to
take advantage of Java 8 syntax possibilities in assertions. -> The
custom assertion class 'PathAssert' as been removed as the identical
behavior is now provided directly by assertJ. Some tests have been a bit
changed to match the assertJ API.

closes [BST-90](https://bonitasoft.atlassian.net/browse/BST-90)