IOT-1476 Remove pthread from sampleserver_randompin

IOT-1476 Remove pthread from sampleserver_randompin

- Using C++ threads as a cross-platform approach
- Added .gitattributes file to ensure *.dat files are binary

Change-Id: I602649d55ee5a8e24a2215d5f68ca5897c9cc6c7
Signed-off-by: David Antler <david.a.antler@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/14055
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Reviewed-by: Dave Thaler <dthaler@microsoft.com>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>