add create and ifexists to line type

cdist/conf/type/__line/gencode-remote

@@ -34,9 +34,17 @@ state_should="$(cat "$__object/parameter/state")"
 state_is="$(cat "$__object/explorer/state")"
 
 if [ -z "$state_is" ]; then
+   if [ -f "$__object/parameter/create" ]; then
+      echo "touch $file"
+   else
+      # only bark if the file should exists
+      if [ -f "$__object/parameter/ifexists" ]; then
+          exit 0
+      fi
       printf 'The file "%s" is missing. Please create it before using %s on it.\n' "$file" "${__type##*/}" >&2
       exit 1
    fi
+fi
 
 if [ "$state_should" = "$state_is" ] || \
 	{ [ "$state_should" = "present" ] && [ "$state_is" = "matching" ] ;} || \

cdist/conf/type/__line/man.rst

@@ -21,6 +21,9 @@ OPTIONAL PARAMETERS
 after
     Insert the given line after this pattern.
 
+create
+    It the file does not exist then create an empty file
+
 before
     Insert the given line before this pattern.
 
@@ -28,6 +31,9 @@ file
     If supplied, use this as the destination file.
     Otherwise the object_id is used.
 
+ifexists
+    Only apply the line if the file exists.
+
 line
     Specifies the line which should be absent or present.