[services-ng] add timeout to query/exec of pg

   1. add timeout to connect/query/exec of pg
   2. support async connect/query/transaction (mutex procted), won't block whole process
   3. lazy close of global connections when using async query

Change-Id: Ifa4bbf2b13b4fa1f68e835ca25a7cb1b3ca8c1f9
Merge "[services-ng] add timeout to query/exec of pg"