Create integration tests

[ybubnov]

The library more or less is covered with unit tests, but is lack of integration tests, therefore in terms of this issue, should be introduced integration tests with Open V-Switch, that cover some scenario of communication between the data plane and control plane.

Also, the tests should require minimal configuration of the development environment. Ideally, it would be nice to describe environment using Dockerfile.

[ybubnov]

Defined an integration test responswrite_test.go used to communicate with Open vSwitch. Need to decide how to setup reproducible environment for this test.