This commit adds support for the change in elasticsearch where the `/` rest
endpoint now delegates to an action and can be authorized.
Original commit: elastic/x-pack-elasticsearch@8ef38ce50f
This commit remove the pre-existing file parsing code and replaces it with the updated
code in the RoleDescriptor class. This unifies the parsing for the files and API for roles.
Closeselastic/elasticsearch#1596
Original commit: elastic/x-pack-elasticsearch@9e0b58fcf1