Make NNA constructor that accepts configuration

[pjeli]

If you take a look at the main class, NNAnalyticsRestAPI.java, particularly here:

NNAnalytics/src/main/java/com/paypal/namenode/NNAnalyticsRestAPI.java

Line 153 in b17e8e6

initAuth(null, null);

You'll see that NNA's bootstrap has a sequence and there are opportunities to override values via parameters. These parameters are set by tests.

It would be nice to refactor this whole bootstrap phase to instead (1) allow a passing of the NNA configuration object SecurityContext (today; to be renamed) and (2) overall simplify testing logic by just calling 1 method to initialize NNA and just passing the desired pre-set configuration object.

Using HDFS's MiniClusters as an example -- we want to simply be able to pass in a configuration object during the bootstrap process for testing. In the production case we will pass null and NNA will utilize the ClassLoader stream method like it does today for loading configuration.

[pjeli]

This has become a priority in order to make #27 and #28 easier to implement.
Bootstrapping NNA should be as simple as passing a configuration and hitting go.

Then in NNAnalyticsRestAPI.java we can focus on just having 1 bootstrap method and allowing use to have access to SecurityContext as part of the routing lambdas is the magic that will make supporting more Authentication mechanisms simpler.

Today there is a disconnect between SecurityContext/Configuration and all the routing static methods so its not feasible to pass needed information.