Add Spectrum as an Adobe Pass provider

Some services no longer allow for the older services (ex.
`Charter_Direct`) to be used and just return a generic 401 response.
Going through their login flow manually, the new provider name appears to
be `Spectrum`. This provider seems to work even place of services that
still allow for `Charter_Direct` to be used.

youtube_dl/extractor/adobepass.py

@@ -60,6 +60,11 @@ MSO_INFO = {
         'username_field': 'IDToken1',
         'password_field': 'IDToken2',
     },
+    'Spectrum': {
+        'name': 'Spectrum',
+        'username_field': 'IDToken1',
+        'password_field': 'IDToken2',
+    },
     'Verizon': {
         'name': 'Verizon FiOS',
         'username_field': 'IDToken1',