Fixed mimetype for robots.txt

ckanext/odsh/views/default.py

 import ckan.plugins.toolkit as toolkit
-from flask import Blueprint
+import ckan.lib.base as base
+from flask import Blueprint, make_response
 import logging
 
 log = logging.getLogger(__name__)
@@ -20,4 +21,6 @@ def not_found():
 
 def robots_txt():
     log.info("views.default::robots_txt")
-    return toolkit.render(u'robots.txt')
+    resp = make_response(base.render('home/robots.txt'))
+    resp.headers['Content-Type'] = "text/plain; charset=utf-8"
+    return resp