Bug#821952: firefox-esr: undistinguishable from firefox in apps menu

[ydirson at free.fr]

Package: firefox-esr, firefox
Version: 45.0.2esr-1, 45.0.2-1

Both firefox and firefox-esr can be installed at the same time, and when they are, we
get 2 "Firefox" entries in the "Internet" apps menu, and even the tooltips are strictly
identical.  There should be a way to distinguish them.

It is especially causing problems today, where a handful of plugins did not gain the "|firefox"
alternative dep and still pull firefox-esr through iceaweal, preventing those that would
like to only have "firefox" installed to do so.