Enable running system test locally and on travis for pull request

[lbustelo]

We currently have a system-test target that is configured to run with SauceLabs. It looks to see if the SauceLabs env variables are set. It currently runs only on Travis as part of a merge into master.

We need to have the following 2 things:

1. A way to run system test locally, without the use of SauceLabs and without having to start anything else to get it to work (i.e selenium). Should be model after make test-js.
2. A way to run system tests on travis for PRs. This should be modeled aftet 'make test-js-remote`. In that target, the tests are fully ran on Travis using selenium and firefox.

I suggest that we use 2 targets as we do with make test-js and 'make test-js-remote'.

[lbustelo]

/cc @peller @aluu317

[aluu317]

We're looking at this

[lbustelo]

I'm removing from milestone... this is not a feature. we can roll this into the branches when ready.