Fix openssl support for encrypted connections

[andreas-bok-sociomantic]

Handshaking

Investigate and implement correctly the authentication process with the MySQL for encrypted connections. This is currently broken as noted here: #286 (comment)

Non-blocking encrypted IO

Reading and writing encrypted data with SSL_read and SSL_write should be non-blocking if the client sets the connection as such.

Add unittests for encrypted connections

Unittests should be added to prevent future bugs in the support for encrypted connections

[smanolache]

I try to address the issue in the following pull request: #345