Support consul backend

[flaccid]

Just a placeholder for this support. Currently there probably only one other UI that supports that.

[AMeng]

I haven't personally used Consul but would definitely accept a PR for this. 😄

[br0ziliy]

@flaccid what's the UI name? I'm interested to have a look.

Big issue is that it's impossible to list configured Consul roles in Vault (there's no /consul/roles?list=true API call in Vault).
The only thing that can be done in vault-web is to have a user specify the exact role name, and return the generated Consul token... Not sure how is this more convenient than vault read consul/creds/rolename CLI command.

[flaccid]

@br0ziliy from what I can see in the community there is currently only 2 Vault UIs out there (this one and https://github.com/nyxcharon/vault-ui). My actual vault knowledge is limited, but from a general perspective I think a graphical frontend (as it usually is) can be quite useful from both a visualization and admin perspective. In this case the consul backend appears to be a popular choice. cc @gobins