plugins tickets import, jp (ticket/import): implemented mapping:

- mapping is an option allowing do map imported field to a specific field in the newly created item
- importers can now use complexe data types in options using JSON

src/plugins/plugin_blog_import.py

@@ -54,6 +54,7 @@ URL_REDIRECT_PREFIX = 'url_redirect_'
 
 class BlogImportPlugin(object):
     BOOL_OPTIONS = (OPT_UPLOAD_IMAGES, OPT_IGNORE_TLS)
+    JSON_OPTIONS = ()
     OPT_DEFAULTS = {OPT_UPLOAD_IMAGES: True,
                     OPT_IGNORE_TLS: False}