debian: added systemd service files.

As it depends on dh-systemd package being available in the distributions, this
bumps operating system requirements to:

 - Ubuntu 14.04+
 - Debian 8+

for debian-based targets.

debian/Makefile

diff --git a/debian/Makefile b/debian/Makefile
index 1ce75e8..0d05e49 100644
--- a/debian/Makefile
+++ b/debian/Makefile
@@ -280,7 +280,7 @@
 		-e 's#%%MAIN_RELEASE%%#$(BASE_RELEASE)#g' \
 		> debuild-base/$(SRCDIR)/debian/changelog ; \
 	cp nginx.control.in debuild-base/$(SRCDIR)/debian/control ; \
-	cp copyright ../CHANGES ../CHANGES.ru nginx.* nginx-debug.default debuild-base/$(SRCDIR)/debian/ ; \
+	cp copyright ../CHANGES ../CHANGES.ru nginx.* nginx-debug.default nginx-debug.service debuild-base/$(SRCDIR)/debian/ ; \
 	chmod +x debuild-base/$(SRCDIR)/debian/rules ; \
 	ln -s debuild-base/$(SRCDIR)/debian/rules rules-base ; \
 	}

debian/nginx-debug.service

diff --git a/debian/nginx-debug.service b/debian/nginx-debug.service
new file mode 100644
index 0000000..f345ce5
--- /dev/null
+++ b/debian/nginx-debug.service
@@ -0,0 +1,16 @@
+[Unit]
+Description=nginx - high performance web server
+Documentation=http://nginx.org/en/docs/
+After=network-online.target remote-fs.target nss-lookup.target
+Wants=network-online.target
+
+[Service]
+Type=forking
+PIDFile=/var/run/nginx.pid
+ExecStartPre=/usr/sbin/nginx-debug -t -c /etc/nginx/nginx.conf
+ExecStart=/usr/sbin/nginx-debug -c /etc/nginx/nginx.conf
+ExecReload=/bin/kill -s HUP $MAINPID
+ExecStop=/bin/kill -s TERM $MAINPID
+
+[Install]
+WantedBy=multi-user.target

debian/nginx.control.in

diff --git a/debian/nginx.control.in b/debian/nginx.control.in
index 56c0f27..d9fbf27 100644
--- a/debian/nginx.control.in
+++ b/debian/nginx.control.in
@@ -3,6 +3,7 @@
 Priority: optional
 Maintainer: Sergey Budnevitch <sb@nginx.com>
 Build-Depends: debhelper (>= 9~),
+               dh-systemd,
                dpkg-dev (>= 1.16.1~),
                quilt (>= 0.46-7~),
                lsb-release,

debian/nginx.service

diff --git a/debian/nginx.service b/debian/nginx.service
new file mode 100644
index 0000000..991207e
--- /dev/null
+++ b/debian/nginx.service
@@ -0,0 +1,16 @@
+[Unit]
+Description=nginx - high performance web server
+Documentation=http://nginx.org/en/docs/
+After=network-online.target remote-fs.target nss-lookup.target
+Wants=network-online.target
+
+[Service]
+Type=forking
+PIDFile=/var/run/nginx.pid
+ExecStartPre=/usr/sbin/nginx -t -c /etc/nginx/nginx.conf
+ExecStart=/usr/sbin/nginx -c /etc/nginx/nginx.conf
+ExecReload=/bin/kill -s HUP $MAINPID
+ExecStop=/bin/kill -s TERM $MAINPID
+
+[Install]
+WantedBy=multi-user.target