Automatically connect input when there is only one (no ambiguity)

[dyollb]

Long story short

I connected the FilePicker (single image file) to the notebook. When I opened the notebook the file is not connected to the input 0.

The file is called "File" (imaging multiple filepicker inputs, could be confusing).

Expected behaviour

It would be convenient if the input was connected when there is only one option.

Actual behaviour

It is not connected.

Steps to reproduce

Pick an image file. Connect to a notebook service.

Note: your environment was attached but will not be displayed

[KZzizzle]

Acceptance Criteria:

Add information about this option in the documentation.

[KZzizzle]

new section in documentation for this point:
http://docs.osparc.io/#/docs/setting_up___running_a_study/connecting_services?id=auto-connect-option