luasec: update to 0.5 to fix memory leak hit by prosody

Noted in luasec 0.4.1 Changelog:
Activate SSL_MODE_RELEASE_BUFFERS by default if it is available (thanks Prosody project)

Update to latest 0.5 to fix a few other leaks.
luasec moved to github, so update URL and license info.
Move package maintainer to correct place in Makefile, hope he is okay with it.

Signed-off-by: Stefan Hellermann <stefan@the2masters.de>