Signed TiddlySaver beta and JavaDocs

Signed TiddlySaver should work with all updates without policy file
except previous broken update 41 (unsigned jar included for that update
will run on medium security).

The security certificate will expire soon, but a new version will be
released.

This version is "wide open" in the same way the original TiddlySaver
was: it has no read/write restrictions on directories. A later version
will include a whitelisting capability.