Update nose-selenium.py

[lunasummer]

I just make it work with python3 , and add some code to show screenshot images in the html report directly. Also add some specific webdivers like ScreenshotOnExceptionFirefoxWebDriver. It works for me now.

[klrmn]

it looks like this patch adds a call to get_screenshot_as_base64() and also leaves the call to get_screenshot_as_file(). i have found screenshots to be very resource-intensive, so i'd like to see some change made so that the config file specifies which kind of screenshot to take.

If it's been changed to work with python3, then additional test environments should be added to tox.ini. I haven't worked with python3, but I'm guessing from the patch that the relevant changes are the imports. I have to wonder if those imports still work for python2.x, since they don't have any try: except or conditionals wrapped around them.

All that being said, I've stopped using this plugin, and this is the first patch / bug report I've gotten on it...would you like to take over ownership?