Hy 1142 rectangle class

Spawned from https://github.com/WebFilings/wf-js-viewer/pull/167


**Jira Ticket:** [HY-1142](https://jira.webfilings.com/browse/HY-1142)

## Problem
Want a simple rectangle class to support hit testing forbidden areas.

## Solution
Created a new Rectangle class that includes a single method to determine if a point is inside the rectangle.

## How to QA/+10
1. CI Build Passes
1. Check out the `HY-1142_rectangle_class` branch
1. Run `./init.sh && grunt qa`
1. Confirm lint and unit tests pass

# Code Review             
@timmccall-wf @lancefisher-wf @robbecker-wf @patkujawa-wf @georgelesica-wf 
The jsdoc comments don't indicate that these are optional, nor does it make sense to me for them to be optional, but either way it'd be good to keep the code and comments in sync.