Replace Output browser with a custom one

* Added ability to choose the application to use for opening a file

(references #79)
Add a Delete option in output browser

* Desactivate popup menu for directories
* Added ability to delete the selected file

(references #79)
Add monitoring in output browser

* Added a monitoring of displayed directory, allowing widget update if changes occurs

(references #79)
Improve of output browser

* Added information on navigation bar
* Added alternate rows color
* Added sorting capability
* Added ability to delete with the "suppr" key, one or many files at once

(closes #79)
Merge branch 'improve-output-browser' of https://github.com/alibres/openfluid into alibres-improve-output-browser