DBSchemaLoader: support enable/disable SSL
This patch will enable use of SSL encryption with the database server, when supported.
A new parameter is enabled by this patch: -useSSL=true|false
Especially useful in MySQL 5.7+ (which doesn't work anyway because of more strict controls on timestamp columns, see tig_users.last_login, I'll open another bug for that) where remote connections automatically enable SSL and generate a warning (not critical, still it's useful to explicitly state that through a parameter).
Based on branch "release".