Use options instead of capabilities to start firefox webdriver
Use options instead of capabilities to start firefox webdriver

This commit modifies the script behind `npm run firefox`
to set the webdriver's moz:firefoxOptions capabilities through
selenium's webdriver interface - namely the firefox.Options class.

closes #1168

darkwing/debugger.html,tomrav/debugger.html,clarkbw/debugger.html,ruturajv/debugger.html,rrandom/debugger.html,ruturajv/debugger.html,borian/debugger.html,ruturajv/debugger.html,jasonLaster/debugger.html,tommai78101/debugger.html,rrandom/debugger.html,jasonLaster/debugger.html,amitzur/debugger.html,tomrav/debugger.html,amitzur/debugger.html,clarkbw/debugger.html,devtools-html/debugger.html,borian/debugger.html,jbhoosreddy/debugger.html,rrandom/debugger.html,bomsy/debugger.html,jasonLaster/debugger.html,jasonLaster/debugger.html,jbhoosreddy/debugger.html,jbhoosreddy/debugger.html,wldcordeiro/debugger.html,kdzwinel/debugger.html,borian/debugger.html,ruturajv/debugger.html,irfanhudda/debugger.html,tommai78101/debugger.html,darkwing/debugger.html,bomsy/debugger.html,kdzwinel/debugger.html,wldcordeiro/debugger.html,wldcordeiro/debugger.html,darkwing/debugger.html,borian/debugger.html,darkwing/debugger.html,bomsy/debugger.html,borian/debugger.html,darkwing/debugger.html,ruturajv/debugger.html,wldcordeiro/debugger.html,amitzur/debugger.html,devtools-html/debugger.html,jasonLaster/debugger.html,wldcordeiro/debugger.html,devtools-html/debugger.html,irfanhudda/debugger.html,jbhoosreddy/debugger.html,bomsy/debugger.html,wldcordeiro/debugger.html,amitzur/debugger.html,jasonLaster/debugger.html,rrandom/debugger.html,rrandom/debugger.html,tommai78101/debugger.html,irfanhudda/debugger.html,devtools-html/debugger.html,devtools-html/debugger.html,tommai78101/debugger.html,bomsy/debugger.html,wldcordeiro/debugger.html,ruturajv/debugger.html,jasonLaster/debugger.html,bomsy/debugger.html,borian/debugger.html,amitzur/debugger.html,clarkbw/debugger.html,jbhoosreddy/debugger.html,kdzwinel/debugger.html,bomsy/debugger.html,irfanhudda/debugger.html,tomrav/debugger.html,clarkbw/debugger.html,devtools-html/debugger.html,amitzur/debugger.html,tomrav/debugger.html,tomrav/debugger.html,ruturajv/debugger.html,darkwing/debugger.html,darkwing/debugger.html,clarkbw/debugger.html,jbhoosreddy/debugger.html,tommai78101/debugger.html,kdzwinel/debugger.html,irfanhudda/debugger.html,jbhoosreddy/debugger.html,devtools-html/debugger.html