[packaging] Missing dnsmasq-base dependency causes wifi hotspot/network sharing feature broken

Impact
=======
In Ubuntu 17.04, the dnsmasq-base dependency has been dropped from network-manager, and the wifi network sharing feature failed to work because of this:

NetworkManager[874]: <error> [1491134643.1581] device (wlp3s0): share: (wlp3s0) failed to start dnsmasq: Could not find "dnsmasq" binary

In my opinion it should at least in Recommends, refer following for related info:

Bug #992411 “network-manager: Please don't Depend on dnsmasq-bas...” : Bugs : network-manager package : Ubuntu
https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/992411

This recommends was dropped here:
https://launchpadlibrarian.net/279417634/network-manager_1.2.2-0ubuntu6_1.2.2-0ubuntu7.diff.gz

Test Case
=========
Install the update and ensure that dnsmasq-base is installed (it is a recommends so it should be pulled in automatically by this update).

This test case requires a laptop (or desktop with Wi-Fi hardware) running Ubuntu 17.04 with an ethernet connection to the Internet.

Open a terminal and run journalctl -f

Then open the Settings app (unity-control-center if running Unity, gnome-control-center if running GNOME) and click the Network panel.

Enable the Wi-Fi hotspot.

Use another device to connect to the Wi-Fi hotspot with the Access Point name and the password presented. Use the Internet on the other device.

There should not be any warnings in the journal output in the terminal about "could not find dnsmasq"

Regression Potential
====================

Other Info
==========
This change was agreed upon by the Ubuntu Desktop Team and Martin Pitt who spearheaded the resolved transition for Ubuntu 17.04.

https://irclogs.ubuntu.com/2017/07/25/%23ubuntu-desktop.html#t13:27
(until 14:45)

This drops a diff with Debian because Debian already recommends dnsmasq-base.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: network-manager 1.4.4-1ubuntu3
ProcVersionSignature: Ubuntu 4.10.0-14.16-generic 4.10.3
Uname: Linux 4.10.0-14-generic x86_64
ApportVersion: 2.20.4-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity:Unity7
Date: Sun Apr 2 20:28:25 2017
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2017-03-30 (2 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Beta amd64 (20170321)
IpRoute:
 default via 192.168.1.1 dev enp4s0f2 proto static metric 100
 10.42.0.0/24 dev wlp3s0 proto kernel scope link src 10.42.0.1 metric 600
 169.254.0.0/16 dev wlp3s0 scope link metric 1000
 192.168.1.0/24 dev enp4s0f2 proto kernel scope link src 192.168.1.119 metric 100
NetworkManager.conf:
 [main]
 plugins=ifupdown,keyfile

 [ifupdown]
 managed=false
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
ProcEnviron:
 LANGUAGE=zh_TW:zh
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=zh_TW.UTF-8
 SHELL=/bin/bash
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 enp4s0f2 ethernet connected /org/freedesktop/NetworkManager/Devices/1 由 DHCP 伺服器自動配發 IP 地址的網路 66cd739f-4bfd-4cbc-909f-1cd96e9ec8bb /org/freedesktop/NetworkManager/ActiveConnection/8
 wlp3s0 wifi connected /org/freedesktop/NetworkManager/Devices/2 林博仁的模擬 Wi-Fi 網路 2547ce2c-a517-4d31-83a2-4bb38fc704cb /org/freedesktop/NetworkManager/ActiveConnection/14
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/0 -- -- --
nmcli-nm:
 RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
 running 1.4.4 connected started full enabled enabled enabled enabled enabled