Allow to update tftpd configuration

This patch reworks tftpd-hpa module to allow specify tftpd
configuration options like:
  username, directory, options

Change-Id: I4fbaa9a4149ca230008099aa29834a8f9de6449b
diff --git a/tftpd_hpa/map.jinja b/tftpd_hpa/map.jinja
index 64fee22..15596b1 100644
--- a/tftpd_hpa/map.jinja
+++ b/tftpd_hpa/map.jinja
@@ -1,21 +1,25 @@
+{% set server = salt['grains.filter_by']({
+    'Common': {
+        'service': 'tftpd-hpa',
+        'path': '/var/lib/tftpboot',
+        'username': 'tftp',
+        'bind': {
+            'address': '',
+            'port': 69
+        },
+        'options': ['--secure']
+    },
+    'Debian': {
+        'pkgs': ['tftpd-hpa', 'syslinux'],
+        'config_file': '/etc/default/tftpd-hpa'
+    },
+    'RedHat': {
+        'pkgs': ['tftp-server', 'syslinux']
+    }
+}, base='Common', merge=salt['grains.filter_by']({
+    'Ubuntu': {
+        'path': '/srv/tftp'
+    },
+}, grain='os')) %}
 
-{%- load_yaml as raw_server %}
-Debian:
-  pkgs:
-  - tftpd-hpa
-  - syslinux
-  {%- if salt['grains.get']('os') == 'Ubuntu' %}
-  path: /var/lib/tftpboot
-  {%- else %}
-  path: /srv/tftp
-  {%- endif %}
-  service: tftpd-hpa
-RedHat:
-  pkgs:
-  - tftp-server
-  - syslinux
-  root: /var/lib/tftpboot/
-  service: tftpd-hpa
-{%- endload %}
-
-{%- set server = salt['grains.filter_by'](raw_server, merge=salt['pillar.get']('tftpd_hpa:server')) %}
+{% do server.update(pillar.tftpd_hpa.get('server', {})) %}