Upload end-to-end test

[UO264345]

Feature description

End-to-end test complying the uploading of files functionality.

Expected behaviour: The test pass.

Other development information, extensions and problems:

• The application is not stable enough for this type of tests, therefore it has to be taken into account that from time to time these tests may fail. Running them again enough times should eventually end in passing tests.
• The test is not accurate enough, as to check that the uploading was correct it will just look for the image link. This doesn't work, as the image can be uploaded several times, and instead, it should look at the image and the date of uploading; but the problem is, the date cannot be looked for since it would need to be retrieved with the same value as the one of the uploaded file, and that is not possible. Therefore, no more accuracy can be achieved.

[UO264345]

The test was already done before the issue was created. It was just created to show that it was done.