update documentation templates for selenium.webdriver.common.*
implemented crazyfun task for generating python api docs

Now it can be run as: go.bat //py:docs
Checked for mswin32 only but sould work everywhere.

Fixes issue 2360.
updated doc strings for selenium.webdriver.common.*

During doc check found and fix bug at Proxy.proxy_type setter:
guard is always checked for AUTODETECT not for passed value.