Py: No-op. Fix, cleanup docstrings.

Especially: mentioning non-existing command.CommandExecutor was replaced by remote_connection.RemoteConnection.
Make de facto required parameter 'desired_capabilities' first parameter in the constructor to highlight it.

Author: sevaseva

py/selenium/webdriver/remote/webdriver.py

@@ -43,22 +43,29 @@ class WebDriver(object):
     https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol
 
     :Attributes:
-     - command_executor - The command.CommandExecutor object used to execute commands.
-     - error_handler - errorhandler.ErrorHandler object used to verify that the server did not return an error.
-     - session_id - The session ID to send with every command.
-     - capabilities - A dictionary of capabilities of the underlying browser for this instance's session.
-     - proxy - A selenium.webdriver.common.proxy.Proxy object, to specify a proxy for the browser to use.
+     - session_id - String ID of the browser session started and controlled by this WebDriver.
+     - capabilities - Dictionaty of effective capabilities of this browser session as returned
+         by the remote server. See https://github.com/SeleniumHQ/selenium/wiki/DesiredCapabilities
+     - command_executor - remote_connection.RemoteConnection object used to execute commands.
+     - error_handler - errorhandler.ErrorHandler object used to handle errors.
     """
 
-    def __init__(self, command_executor='http://127.0.0.1:4444/wd/hub',
-        desired_capabilities=None, browser_profile=None, proxy=None, keep_alive=False):
+    def __init__(self, desired_capabilities=None, command_executor='http://127.0.0.1:4444/wd/hub',
+                 proxy=None, browser_profile=None, keep_alive=False):
         """
         Create a new driver that will issue commands using the wire protocol.
 
         :Args:
-         - command_executor - Either a command.CommandExecutor object or a string that specifies the URL of a remote server to send commands to.
-         - desired_capabilities - Dictionary holding predefined values for starting a browser
-         - browser_profile - A selenium.webdriver.firefox.firefox_profile.FirefoxProfile object.  Only used if Firefox is requested.
+         - desired_capabilities - A dictionary of capabilities to request when
+             starting the browser session. Required parameter.
+         - command_executor - Either a string representing URL of the remote server or a custom
+             remote_connection.RemoteConnection object. Defaults to 'http://127.0.0.1:4444/wd/hub'.
+         - proxy - A selenium.webdriver.common.proxy.Proxy object. The browser session will
+             be started with given proxy settings, if possible. Optional.
+         - browser_profile - A selenium.webdriver.firefox.firefox_profile.FirefoxProfile object.
+             Only used if Firefox is requested. Optional.
+         - keep_alive - Whether configure remote_connection.RemoteConnection to use
+             HTTP keep-alive. Defaults to False.
         """
         if desired_capabilities is None:
             raise WebDriverException("Desired Capabilities can't be None")