Add of an empty Output browser tab

(references #79)
Add of a basic FileChooser for Output browser

(references #79)
Add the path and a reset button to output browser

(references #79)
Removal of plugin file checking when adding an Observer
Merge branch 'remove-addObserver-check' of https://github.com/alibres/openfluid into alibres-remove-addObserver-check
Merge branch 'develop' into devel-market