Replace command parameters with values

To create a minimalistic parser, nom is used to identify and replace
parameters given in the command field.

For clarity the `action` field for hooks was renamed to `command`.

config.yml

@@ -1,7 +1,7 @@
 ---
 hooks:
   hook1:
-    action: /usr/bin/local/script_xy.sh
+    command: /usr/bin/local/script_xy.sh {{ /field2/foo }} asdfasdf
     secrets:
       - secret_key_01
       - secret_key_02
@@ -10,7 +10,16 @@ hooks:
         pointer: /ref
         regex: refs/heads/master
   hook2:
-    action: /usr/bin/local/script_xyz.sh
+    command: /usr/bin/local/script_xy.sh asdfasdf
+    secrets:
+      - secret_key_01
+      - secret_key_02
+    filters:
+      match_ref:
+        pointer: /ref
+        regex: refs/heads/master
+  hook3:
+    command: /usr/bin/local/script_xyz.sh
     secrets:
       - secret_key03
     filters: