cmake: use the OpenSSL module provided by CMake

Remove custom FindOPENSSL.cmake module provided by vishnu
fixes #366
TMS client: fix cancel_job error message when machineId may be incorrect

vishnu_cancel_job wasn't able to distinguish incorrect machineId from other
errors which may be confusing for users. Now it's fixed :o)
tms client: contact the right TMS when you provide the machine id

A regression introduced by the zeromq backend, it always contact
the first TMS server listed in the configuration without checking
the machine id. Now it takes the first one with machine id.
tms client: if we don't have the proper machine id, use dispatcher

If we try to contact a machine-specific service and it's not in
configuration file, we just ask friggin' dispatcher