[VersionConv] Change exception type

Closes #359

Changed plain Exception in '_parse' to
odml.tools.parser_utils.ParserException.

Author: mpsonntag

odml/tools/converters/version_converter.py

@@ -12,6 +12,8 @@
 
 from lxml import etree as ET
 
+from ..parser_utils import ParserException
+
 from ...format import Document, Section, Property
 from ...info import FORMAT_VERSION
 from ...terminology import Terminologies, REPOSITORY_BASE
@@ -52,7 +54,7 @@ def _parse_xml(self):
             tree = ET.parse(self.filename, parser)
         else:
             msg = "Cannot parse provided file object '%s'." % self.filename
-            raise Exception(msg)
+            raise ParserException(msg)
 
         return tree