Release the connection when ogr2ogr is working , and maintain the same connection through all of query in API

[kshitijrajsharma]

With the connection pooling for each request , even though the small query should share the same connection and and make sure they don't leak the memory + connection when they do that ! And also when ogr2ogr launches it fires up multiple connection to fetch data , now API needs to take care of the connection and close it even though ogr2ogr fires up new connection , And when process finishes up it needs to come back and put connection to the pool