More tools

Now it only supports reading raw values.
Other modes will be added in future versions

Tools

Performs OPC UA browse and prints results.
For example:
tools/ls.py opc.tcp://example.org:4840/OpcUa "i=85"

Performs OPC UA discover and prints results.
For example:
tools/discover.py opc.tcp://example.org:4840

In get_endpoints(): don't set ProfileUris (get all available endpoints)
and don't set LocaleIds (the value was wrong anyway).
In get_server_endpoints(): disconnect socket in the end.

add script for generating debian package