Allow user to specify which version of SSL protocol to use by setting
libcloud.security.SSL_VERSION variable (we still default to
ssl.PROTOCOL_TLSv1).
Merge branch 'trunk' of https://git-wip-us.apache.org/repos/asf/libcloud into trunk
Global IP addresses handling in the GCE driver.

Closes #394

Signed-off-by: Tomaz Muraus <tomaz@apache.org>