Create /var/run/reboot-required file

Fix #195

tracer/controllers/default.py

@@ -69,6 +69,7 @@ def render(self):
 			view.assign("applications", self.applications)
 			view.assign("args", self.args)
 			view.render()
+			self.create_reboot_required_file()
 		exit(self.status_code())
 
 	def render_helpers(self):
@@ -136,6 +137,15 @@ def status_code(self):
 			code = 104
 		return code
 
+	def create_reboot_required_file(self):
+		"""
+		If a reboot is needed, create a /var/run/reboot-required file.
+		This is how Debian/Ubuntu distros does it.
+		"""
+		if self.applications.count_type(Applications.TYPES["STATIC"]):
+			with open("/var/run/reboot-required", "w") as fp:
+				fp.write("Tracer says reboot is required\n")
+
 	def _restartable_applications(self, applications, args):
 		return applications.exclude_types([
 			Applications.TYPES['STATIC'],