smt-client: make http timeout work in smt-agent also for the SSL handshake

fixing bnc#876609

Background:
The http timeout has no effect during the actual SSH handshake.
So a bad connection at the right moment could lead to an smt-agent
process to get stuck forever.

References:
http://perlmonks.org/?node_id=956556
http://stackoverflow.com/questions/9400068/make-timeout-work-for-lwpuseragent-https

The issue is fixed upstream in the latest versions.
This commit adds a workaround to smt-client.
smt-client changes: make http timeout work during SSL handshake (bnc#876609)