fix(buildArray): Support tuple arrays

JSON Schema provides support for [tuple validation](https://spacetelescope.github.io/understanding-json-schema/reference/array.html#tuple-validation);
however, this module previously lacked support for it.

This commit will allow arrays to either be of a single type or to
be of mixed types in the order specified by the schema.

Note that uglify is unnecessary on node 8.3.0

Handle null when value should be string

Avoid calling substring to remove a comma.

Fixes #15

If a value is undefined, it shouldn't be passed to fastSafeStringify

Add ability to uglify generated code

Allow non alpha keys

Allow specifying deep additionalProperties=true

Fixes #33

Support for long integers

Faster string serialization

Optional properties support

Update standard to the latest version 

https://greenkeeper.io/

Added Greenkeeper