nginx logrotate fixup

* Set postrotate script to SIGHUP nginx after rotation
* Explicitly set permissions on freshly created logfiles

playbooks/roles/nginx/templates/edx_logrotate_nginx_access.j2

 # Put in place by ansible
 
 {{log_base_dir}}/nginx/access.log {
-  create
+  create 0640 www-data adm
   compress
   delaycompress
   dateext
@@ -10,4 +10,9 @@
   daily
   rotate 90
   size 1M
+  sharedscripts
+  postrotate
+	[ ! -f /var/run/nginx.pid ] || kill -HUP `cat /var/run/nginx.pid`
+  endscript
 }
+

playbooks/roles/nginx/templates/edx_logrotate_nginx_error.j2

 # Put in place by ansible
 
 {{log_base_dir}}/nginx/error.log {
-  create
+  create 0640 www-data adm
   compress
   delaycompress
   dateext
@@ -10,4 +10,8 @@
   daily
   rotate 90
   size 1M
+  sharedscripts
+  postrotate
+	[ ! -f /var/run/nginx.pid ] || kill -HUP `cat /var/run/nginx.pid`
+  endscript
 }