Unstable Selenium plugin in Nutch. Fixed bugs and enhanced configuration

Issues:
(a) Firefox browser doesn't close gracefully.
(b) The property libselenium.page.load.delay is not working. No matter how much delay you give, the driver is not waiting for the page to load.
(c) There is no timeout configured for the firefox binary.
(d) A lot of selenium configuration is hard-coded which can be exposed through nutch-default.xml or nutch-site.xml

All these issues are part of "lib-selenium" plugin which is being used by two other protocols "protocol-selenium" and "protocol-interactiveselenium".