issue #83: moved logic to convert bytes to str to Resource instead of…

… in Insert's init

cloudofficeprint/elements/elements.py

@@ -921,7 +921,7 @@ class Insert(Property):
     """
 
     def __init__(self, name: str, value: Resource):
-        super().__init__(name, value.base64 if isinstance(value, RawResource) else value.data)
+        super().__init__(name, value.as_string)
 
     @property
     def available_tags(self) -> FrozenSet[str]:

cloudofficeprint/resource.py

@@ -46,6 +46,18 @@ def data(self) -> Union[str, bytes]:
         """
         return self._data
 
+    @property
+    def as_string(self) -> str:
+        """The string representation of the data contained in this Resource.
+
+        Returns:
+            str: the string representation of the data contained in this Resource.
+        """
+        if isinstance(self.data, str):
+            return self.data
+        elif isinstance(self.data, bytes):
+            return file_utils.raw_to_base64(self.data)
+
     @property
     def template_json(self) -> str:
         """Get the JSON representation when used as a template.