Add the capability to construct a new process object given a pid: new OSProcess(pid).

Steps to implement:

1. Write a new constructor that takes a pid as an argument, sets the processID attribute, and calls an updateAttributes() method.
2. Write a new public updateAttributes() method which calls the platform-specific getProcess(this.processId) and then copies all the values from the return value OSProcess to the class attributes. You'll have to switch based on SystemInfo.getCurrentPlatformEnum().