#137 - Adding strict null checks compiler option and fixing resulting errors.

[brandongk]

@ryanluker - I don't think this fixes #137 at this point, but it's a start.

Issue:

137

Turning on typescript strictNullChecks option to deal with the undefined issues.

https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html

I had to make a bunch of changes to get this compiling after turning this option on.

[ryanluker]

@brandongk60 just the one comment about the test we can probably remove then this is good to merge.