optionally disable sqlite encryption

I'm working on OSX box with ports, and cannot use brew, ports and brew collide.
All the dependencies work, except pysqlcipher.
It compiles fine, but if pragma key is used, silently fails to create db.
This looks like some linkage hell, but since encryption of local db is using hard-coded password, and doesn't add too much anyway, I've added an optional flag to disable it.
No productional value, but might be helpful for troubleshooting.