Increase number of browsers tested

[jgadsden]

It would be good to increase the number of browsers we test against, at present it is:

• Chrome
• Firefox
• IE
• PhantomJS Consider using Karma-detect-browsers: https://www.npmjs.com/package/karma-detect-browsers to increase coverage to:
• Opera
• Safari
• Edge

[jgadsden]

Migrated to new issue in the OWASP area repo : https://github.com/OWASP/threat-dragon-core/issues/15