Use Tempfile for socket tests

[voxik]

There is a quite small limit on socket path. This leeds to test error such as the one bellow on deeply nested systems.

  1) ABRT #handle_exception logs error into syslog when can't communicate with ABRT daemon because no-one is listeing on the other side
     Failure/Error: expect(syslog).to receive(:err).with("%s", /can't communicate with ABRT daemon, is it running\? Connection refused -( connect\(2\) for)? "?#{socket_path}"?/)

       #<Double "syslog"> received :err with unexpected arguments
         expected: ("%s", /can't communicate with ABRT daemon, is it running\? Connection refused -( connect\(2\) for)? "?\/bui...ygem-abrt-0.5.0-build\/abrt-0.5.0\/usr\/share\/gems\/gems\/abrt-0.5.0\/spec\/abrt_handler_spec.rb"?/)
              got: ("%s", "can't communicate with ABRT daemon, is it running? too long unix socket path (114bytes given but 108bytes max)")
       Diff:
       @@ -1,3 +1,3 @@
        ["%s",
       - /can't communicate with ABRT daemon, is it running\? Connection refused -( connect\(2\) for)? "?\/builddir\/build\/BUILD\/rubygem-abrt-0.5.0-build\/abrt-0.5.0\/usr\/share\/gems\/gems\/abrt-0.5.0\/spec\/abrt_handler_spec.rb"?/]
       + "can't communicate with ABRT daemon, is it running? too long unix socket path (114bytes given but 108bytes max)"]
     # ./spec/abrt_handler_spec.rb:140:in 'block (5 levels) in <top (required)>'