DistributionConfig and Geode system properties

[Udo Kohlmeyer]

Hi there,

As per GEODE-1377 <https://issues.apache.org/jira/browse/GEODE-1377> 
I've refactored DistributionConfig to extract all public system 
properties into a public DistributedSystemConfigProperties interface.

With that refactor I've touched a significant amount of classed and I, 
in advance, apologize for the merging.

I've have tried to find all references to all the properties that we use 
within Geode (be it main and test).

For future development, if we are to use and system properties, that we 
use the provided definition for that property. That will help us to 
understand where the properties are used and will make it easier if we 
need to refactor anything in the future.

I've also tried to find every reference to "gemfire." and replaced it 
with its defined counterpart. This should hopefully help us if we were 
to move away from property definitions like "gemfire.locators" to 
"geode.locators". If someone were to find that I had missed an obvious 
property to please refactor and resolve that issue.

In addition to this effort I have noticed that we use a large amount of 
properties to configure functionality. I respectfully request from all 
developers that if you were to work on some code that uses "internal" 
properties to maybe pull it out into a common interface which can be 
reused throughout the code base.

--Udo