Passing key and certificate to hydra

[janekolszak]

As discussed here: https://groups.google.com/forum/#!topic/ory-hydra/GmAR-9yUALo

Please add a way to pass Hydra key and certificate on startup. For example

hydra host --key key.pem --cert cert.pem

[aeneasr]

additionally, keys should be passed through env vars

TLS_KEY_PATH
TLS_CERT_PATH

[janekolszak]

and saved I guess in case hydra is restarted

[aeneasr]

the keys will be imported to the JWK store. we need to figure out if the key from JWK store overrides the key from disk when changed or the other way around

[aeneasr]

it's probably smarter to call the option import-tls-key instead.

[aeneasr]

upstream #92