This PR reworks the web layout so static files can be provided and
a "themes" directory to allow a certain degree of control over logos,
styles, etc.
This PR does NOT add general support for frontend customization,
only enough to allow us to start exploring theming internally.
The dex binary also must now be run from the root directory since
templates are no longer "compiled into" the binary.
The docker image has been updated with frontend assets.
Bcrypt'd hashes have "$" characters in them. This means that #667
(accepting actually bcrypted values) combined with #627 (expanding
config with environment variables) broke the example config.
For now, allow storages and connectors to expand their configs from
the environment, but don't do this anywhere else.
ghodss/yaml converts from YAML to JSON before attempting to unmarshal.
This allows us to:
* Get the correct behavor when decoding base64'd []byte slices.
* Use *json.RawMessage.
* Not have to support extravagant YAML features.
* Let our structs use `json:` tags
Allow users to define config values which are read form environemnt
variables. Helpful for sensitive variables such as OAuth2 client IDs
or LDAP credentials.
