Add entity_alias to create_token

[thomaslarsen]

The entiry_alias parameter seems to be missing on the create_token method.

This us used in conjunction with the allowed_entity_aliases in the create_token_role method to bind the token to an entity.

When I try to use the entiry_alias parameter, I get an error like this:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/src/app/flask_app/vault.py", line 130, in get_pipeline_token
    token_response = self.client.create_token(
TypeError: create_token() got an unexpected keyword argument 'entity_alias'

which is probably not surprising as it isn't defined on the method...