Make it easy to use the clients with SystemLink client application

[santhoshramaraj]

When run on a SystemLink server, the Clients are intelligent enough to automatically pick the URI and API Key, but the same doesn't apply when the code is run on a remote system with a SystemLink client application connected to a SystemLink.

The following snippet works only when running the server

from nisystemlink.clients.dataframe import DataFrameClient
client = DataFrameClient()

The following snippet is required to work on the client

from nisystemlink.clients.dataframe import DataFrameClient
from nisystemlink.clients.core import HttpConfigurationManager
client = DataFrameClient(HttpConfigurationManager.get_configuration())

[santhoshramaraj]

Addressed as part of PR #61