Fix recurent problem of port not free when starting mongo daemon.
Fix recurent problem of port not free when starting mongo daemon.

For instance:
https://test.savoirfairelinux.com/job/Shinken-Upstream-Commit-Short-Tests/697/testReport/junit/%3Cnose/suite/ContextSuite_context_TestConfigSmall__setup/

simply create a new socket with random port selection, and use that port for the mongo daemon.

staute/shinken-mod-logstore-mongodb,shinken-monitoring/mod-logstore-mongodb,staute/shinken-mod-logstore-mongodb,shinken-monitoring/mod-logstore-mongodb