Run unit tests on Sauce (closes #289)
Run local ptor tests in Firefox

Travis can run FF but not Chrome
only run sauce tests when an access key is present

this prevents PRs from forks from failing because they lack access to the secure travis env
Move browser settings into separate config file
remove unnecessary conditional check
browser + ptor fixes
remove sauce keys so a local WD is used
Remove casper
Run grunt install before_script so Selenium Standalone is available
Merge pull request #331 from bendrucker/sauce

Run unit tests on Sauce