Additional API interfaces and implementations


	
This should get us up to speed on most of the API stuff, in this PR we've got interfaces and implementations for: 
* Motors 
* Gyroscopes 
* Distance Sensors 
 
The only thing missing from last years robot is the accelerometer 
 
It also adds the `LimitedMotor` composite class and JUnit test cases, which though similar in concept to `SolenoidWithPostion`, isn't worth trying to abstract. 
 
Aside from that I fixed some documentation and refactored Hardware so that similar factory methods are in nested classes. 
 
Some things that might be worth considering: 
* The `Hardware` and `Mock` prefixes are a little overkill, the names are different enough to prevent conflicts, and if not, they're in separate packages. 
* If we are going to rely on the accelerometer and gyroscope more heavily then last year, it might be beneficial to have some helper classes that allow us to attach units and direction to a value, e.g. `Angle`, `Velocity`, `Displacement`, etc. 
No, we definitely don't want to store a speed. Rather we do want to get the *actual* speed of the motor (or whatever it returns), and for `HardwareMotor` that would be calling `speedController.getSpeed()` and ultimately the code I highlighted in my previous comment. My concern is that even if the motor is standing still, the motor controllers might via the `PWM.getSpeed()` implementation compute and return a double value that is effectively but not exactly equal to 0.00000000, but is instead close. This error would be due to the computation.

It's probably not worth haggling over, so I'm fine with continuing to use 0.0 for the literal value.