1. Add _opt_reconnect to connection class for better reconnection (handle situation, when server closes connection)
2. Add "not_presented" and "presented" flags into Insert operation
Moving Ping to separate operation, so we have only one way to send requests
Fixes for previous commits. Add support of select all tuples in fields for TREE index (via empty tuple)
Add flags support. Split operation replace, store, insert from one insert
pylint'ing and pyflaks'ing sources. Add some docstrings and pep8'fying code
Set return_tuple flag, by default, to True