Initial deploy for systemd fails since #47

When deploying an app for the first time there is no systemd target to stop at

capistrano-twingly/lib/capistrano/twingly/tasks/service.rake

Lines 24 to 32 in 11c33c4

    
           on roles(:systemd) do 
        
             sudo :systemctl, "stop #{fetch(:application)}.target" 
        
             within current_path do 
        
               sudo fetch(:chruby_exec), "#{fetch(:chruby_ruby)} -- #{fetch(:bundle_binstubs)}/foreman export systemd /etc/systemd/system -a #{fetch(:application)} -u \`whoami\` -l #{shared_path}/log" 
        
             end 
        
             sudo :systemctl, "daemon-reload" 
        
           end

which makes the task fail with the following error:

sudo stderr: Failed to stop twingly-test.target: Unit twingly-test.target not loaded.

We should only run systemctl stop if the target can be found (ie. the application has been deployed before). I'm sure there is a good way to determine if that is true.

This bug was introducced in #47

	on roles(:systemd) do
	sudo :systemctl, "stop #{fetch(:application)}.target"

	within current_path do
	sudo fetch(:chruby_exec), "#{fetch(:chruby_ruby)} -- #{fetch(:bundle_binstubs)}/foreman export systemd /etc/systemd/system -a #{fetch(:application)} -u \`whoami\` -l #{shared_path}/log"
	end

	sudo :systemctl, "daemon-reload"
	end