Enable tsc in ci pipeline take 2

[duluca]

• Changed package.json command to build test.ts into test.js, use
  node to execute the file to verify correct function, then clean up the
  file (unfortunately it is not possible to use the generated folder to
  do this, otherwise dev experience of test.ts breaks given the
  relative location of td)
• Updated gitignore to ignore .vscode (I didn’t add
  test/src/typescript/test.js since if tests are successfully passing
  this file shouldn’t exist, but could be added as a defensive measure)
• Updated test.ts to fix broken or invalid test double code. It seems
  that .constructor() now requires the usage of .prototype in front
  of function names, not sure if this is a recently introduced bug or not.
• Added mocha and chai typings to make it possible to add actual unit
  tests to test.ts — for now implemented a simple assert

[duluca]

@searls now seem to be a different set of failures. Looked into it for a while but no dice.

1. Node 4 build seems to fail due to 'no proxy support' -- given my local experiments, it seems that test double is not compatible with Node 4 (at least in the context of TypeScript compiling a class down to ES 5)

var Bear = (function () {
    function Bear() {}
    Bear.prototype.sleep = function () {}
    return Bear;
}());

var bear = td.object("Bear");

​​Error: testdouble.js - td.object - The current runtime does not have Proxy support, which is what​​
​​testdouble.js depends on when a string name is passed to `td.object()`.​​

2. Not sure why the Node 6 builds fails due to a seeming timeout issue, but Node 7 build passes

[searls]

FWIW, I am able to repro the Node 4 failure locally. Disregard the Node 6 failure, I have a flaky unit test that's somehow triggering a timeout.

[searls]

Fixed and merged (I made a couple commits)

[duluca]

@searls awesome thanks