svn-support: Move try/catch block up to subscriber and also DB interaction.

svn-support: Use utf-8 to encode mod_dav_svn configuration before writing to disk. Repository or group names may contain non ASCII characters. Therfore we have to encode the configuration before writing it to the file.

svn-support: Fix typo in argument name.

svn-support: Delete last traces of removed setting.

svn-support: Remove settig from configuration file templates.

svn-support: Use repo root path from DB to generate mod-dav-svn config. Fixes #4203

polymer: moving imports for better performance

tests: fixing changelog test for new notifications

notifications: switch to embedded alerts for HTTPNotFound

notifications: move all notifications into polymer for consistency fix #4201