Templatize sieve rules editor; return success/fail state of serverwrite

Templatize sieve rules editor; return success/fail state of serverwrite

 - return status of sending stuff to citserver, so we can abort loops in time if our connection dies.
 - add sieve scripts lists with content to the session for one request
 - add hooks for listing sieve scripts and their contents
 - add parser for our webcit embedded sieve editor
 - add hooks for our webcit embedded sieve editor
 - add templates with the contents from sieve.c