Remove usr/lib/*/nemo/nemo-extensions-list from nemo.install

[pdenapo]

This is a followup of my previous PR #3400

In order to successfully build the .deb packages for nemo from the sources (using fakeroot ./debian/rules binary)
this other change is requiered, since otherwise one gets the following error message (aborting the building process)

dh_install
dh_install: warning: Cannot find (any matches for) "usr/lib/*/nemo/nemo-extensions-list" (tried in ., debian/tmp)

dh_install: warning: nemo missing files: usr/lib/*/nemo/nemo-extensions-list
dh_install: error: missing files, aborting
make: *** [debian/rules:19: binary] Error 255

This is so, because now the extensions are kept in a separate repository with their own .deb packages

https://github.com/linuxmint/nemo-extensions

[mtwebster]

This isn't necessary - I'm not sure why you're having trouble building this, but:

• nemo-extensions-list is not an extension, it's a helper for nemo detecting installed extensions. It belongs in the nemo package, and is not optional.
• Please don't modify the debian changelog, this is only done prior to a version tag.

Speaking of the changelog, we aren't affiliated with Ubuntu in any way, as far as this package goes, so we would never use an ubuntu revision. I checked the debian and ubuntu packaging, and neither of them patch any part of the debian packaging here.