Add a "drivers" folder for storing web drivers

Author: mdmintz

drivers/ReadMe.md

@@ -0,0 +1,13 @@
+### SeleniumBase web driver storage
+
+* Usage:
+
+```bash
+seleniumbase install chromedriver
+seleniumbase install geckodriver
+seleniumbase install edgedriver
+```
+
+After running the commands above, web drivers will get downloaded into this folder. SeleniumBase will then use those drivers during test runs if present. (The drivers don't come with SeleniumBase by default.)
+
+If the necessary driver is not found in this location while running tests, SeleniumBase will instead look for the driver on the System PATH. If the necessary driver is not on the System PATH either, you'll get errors.

drivers/__init__.py

@@ -43,6 +43,7 @@
               'seleniumbase.masterqa',
               'seleniumbase.plugins',
               'console_scripts',
+              'drivers',
               'integrations',
               'integrations.selenium_grid',
               'integrations.selenium_ide',