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/server.sls b/tftpd_hpa/server.sls
index eb716d3..a022d18 100644
--- a/tftpd_hpa/server.sls
+++ b/tftpd_hpa/server.sls
@@ -5,10 +5,24 @@
   pkg.installed:
   - pkgs: {{ server.pkgs }}
 
+{{ server.config_file }}:
+  file.managed:
+    - name: {{ server.config_file }}
+      source: salt://tftpd_hpa/files/tftpd-hpa.conf
+      template: jinja
+
 tftpd_hpa_service:
   service.running:
   - name: {{ server.service }}
   - enable: true
   - running: true
+  - watch:
+      - file: {{ server.config_file }}
 
-{%- endif %}
\ No newline at end of file
+{{ server.path }}:
+  file.directory:
+  - makedirs: True
+  - name: {{ server.path }}
+  - user: {{ server.username }}
+
+{%- endif %}