all: manage all outgoing requests in one place

I know, I know. Huge PR. I'm sorry :(

**This depends on #276.**

This gets rid of the connection module, and uses the abstracted [google-service-account](https://github.com/stephenplusplus/google-service-account). I know we talked about bringing back support for pem files, so when that time comes, I can just add it in the gsa lib.
Network attempts of any kind.

On Thursday, November 6, 2014, Ryan Seys <notifications@github.com> wrote:

> In test/common/util.js:
>
> > +        gsa_Override = function() {
> > +          return function authorize(reqOpts, callback) {
> > +            callback(error);
> > +          };
> > +        };
> > +
> > +        var makeRequest = util.makeAuthorizedRequest();
> > +        makeRequest({}, function(err) {
> > +          assert.equal(err, error);
> > +          done();
> > +        });
> > +      });
> > +
> > +      it('should try to reconnect if token invalid', function(done) {
> > +        var attempts = 0;
> > +        var expectedAttempts = 2;
>
> What attempt count is this? Is attempts to make the request or attempts to
> get a token? Token refresh attempt count is set to 1 above but this is two.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/GoogleCloudPlatform/gcloud-node/pull/278/files#r19973572>
> .
>