fix race condition on uploaded file
Merge pull request #1740 from conejoninja/move_uploaded

fix race condition on uploaded file
removed OSC_CRYPT_KEY, added alert public and private key to session, added alert signature validation on server side, minor improvements
fixed issue on contact page, without attachements always return error
fix notice on phpseclib, The plaintext's length (XX) is not a multiple of the block size (32), minor fixes
Merge remote-tracking branch 'upstream/hotfixes' into develop