[nemo-fileroller] Support engrampa as fallback if file-roller cannot be found

[ntninja]

Currently nemo-fileroller simply does not work if file-roller is not installed. While that is (generally) fine, it would be nice if it could support using engrampa as a fallback. Since engrampa is a file-roller fork (by the MATE project), it has a 100% compatible command-line API and mimics file-roller in everything but the binary name (which in turn is hard-coded into nemo-fileroller). If you agree that it would be OK for nemo-fileroller to fallback to engrampa I could provide a patch for that.

In case you don't agree: Would you consider hosting a nemo-fileroller fork in nemo-extensions (i.e.: nemo-engrampa) that provides support for extracting archives with engrampa?

[juanfgs]

Hello I've taken this task to myself since I use nemo on the Mate desktop.

I've basically taken the original extension and replaced the commands, then created a new extension https://github.com/juanfgs/nemo-engrampa . It works, altought from what I see it loses localization.

If you guys consider this might be useful for better integration with other desktops feel free to integrate it to the repo (or let me know the appropiate way to contribute to your project )

Thanks!