Use firefox options for capabilities as well.

firefox specific options (--profile, --profire-dir and --firefox) are can be used for RemoteWebDriver
(See https://code.google.com/p/selenium/wiki/DesiredCapabilities#Firefox_specific ), 
I moved creating Firefox profile code from FirefoxDriverFactory to DriverOptinos and added
code to set firefox capabilities to DriverOptions.

This change makes selenese-runner to set firefox capabilities always when firefox options are specified,
but I believe this makes any negative effect since all of the web drivers other than FirefoxDriver may
ignore firefox capabilities.