Allow passing a boolean value to desired capabilities

Allow passing a boolean value to desired capabilities

• All formats as of now:
  'KEY': 'VALUE'
'KEY': True
'KEY': False
caps['KEY'] = "VALUE"
caps['KEY'] = True
caps['KEY'] = False
  (Each pair must be on a separate line. You can interchange single and double quotes.)
  See https://github.com/seleniumbase/SeleniumBase/tree/master/examples/capabilities for the full ReadMe and sample capabilities files.