Token authentication support
There are a couple of areas where token authentication support is needed.
- get_grid_credentials_if_needed() needs to not only get x509 certs/proxies
as needed, but get tokens checking/setting $BEARER_TOKEN and $BEARER_TOKEN_FILE
as appropriate (see https://github.com/WLCG-AuthZ-WG/bearer-token-discovery/blob/master/specification.md)
- the suitable kx509 equivalent for tokens needs to be used in the above
- an ifdh getToken call should be added, to go with getProxy
- The www_cp.sh script should set "Authorization: Bearer ..." headers appropriately
for a token set as above when calling curl
- ifdh for now should send both types of authentication if available, and let the
service figure out what it can use.