Add cli tests for existing TLS behaviour

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Rename host-based auth to identity-based auth

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Whitespace fixes

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Update cert-based auth docs to use new options

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Fix comment formatting

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Move default flag values to flags.go

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Add auth option to switch between auth methods

- Can switch between "identity", "cert" and "none"
- Replaced --insecure with --auth=none
- Moved logic to generate TLS configs to separate auth files

Signed-off-by: Ben Firshman <ben@firshman.co.uk>
Prefix TLS options with --auth

--tlscert -> --auth-cert
--tlskey -> --auth-key
--tlscacert -> --auth-ca

Signed-off-by: Ben Firshman <ben@firshman.co.uk>