Ubuntu fixing Firefox flash "This plugin is vunerable and should be updated"

Recently Firefox wasn't working with Flash.  I was getting "This plugin is vunerable and should be updated."

For the life of me, I couldn't figure out what was wrong.  Finally did the nuclear option.

> sudo apt-get remove --purge flashplugin-installer
> sudo apt-get install flashplugin-installer

then restarted my machine.  All fixed.

Clearing DHCP leases on Ubuntu (14.04 Trusty Tahr)

Got a new router from my provider today.  All my other wireless devices (tablet, printer, etc.) connected up fine to the new router, but for some reason my Ubuntu laptop wouldn't.

When I plugged in an ethernet cable, everything was fine, DHCP was working fine.

Eventually a noticed that for some reason the DHCP lease for the Wifi was not clearing and I was getting an old IP address.

Eventually via some simple Google searches learned that you should clear old DHCP leases in /var/lib/dhcp.

But for some reason that wasn't working ... what else was I missing?

After some trial and error, the key was also clearing the leases stored in /var/lib/NetworkManager.

Hopefully this proves useful for someone out there in the Internet.  I'm sure there are some pretty GUI based ways to do this, but I'm not a GUI person and was unaware of how to do it that way.