luci-app-fwknopd: Client-side rendering and improvements/fixes.

luci-app-fwknopd: Client-side rendering and improvements/fixes.

 * Use client-side rendering.
 * Asynchronous QR code generation and on-the-fly updates.
 * Added button to generate keys.
 * Added keys validation (empty, __CHANGEME__ and CHANGEME values are not
   valid).
 * Added SOURCE option non-empty validation (SOURCE is mandatory field).
 * Added network and DESTINATION options.
 * Use checkboxes for Y/N options instead of text fields.
 * Fix the qrencode tool, which currently has only `--inline` option, not
   `-I`. Use `--inline` instead.
 * Improve configuration handling by removing the key type from the config
   file. The key type is deduced from the actual values (normal/base64).
 * Provide migration script (clean-up of stale keytype/hkeytype values in
   config).
 * Fixed usage of translations.

Signed-off-by: Oldřich Jedlička <oldium.pro@gmail.com>