Ingest SDK sample hello world client

[varun-ganesh]

Initial set of changes introducing a sample client to read credentials from ~/.snow/config

This is mainly inspired from the aws sdk where they store credentials in ~/.aws/credentials and the sample client application that they have put out. The changes consist of 3 classes:

1. Snowconfig - Loads the configuration information from ~/.snow/config
2. SnowIngestClient - Just stuff pulled from the Unit test for now. Will be adding more stuff here:
   a. Ability to use an S3 stage.
   b. Ability to ingest several files.
   c. Do History paging using the marker scheme.
3. SnowSample - This is the sample application I intend to be made available for customers to look at to start using the ingest service. I intend to follow up and make this stand alone.

Once this change is in, I will make SnowSample standalone, do improvements and additions to SnowIngestClient, SimpleIngestManager and update Ingest History response. Once these are done, then we can do importing into Maven and add tests to Jenkins.