Removing the key id from when only one secret/algorithm is supplied

When only one algorithm is passed into the configuration but multiple secrets are provided the algorithm
array then needs to be manipulated into a key value store, using the key from the secrets list and the
algorithm being used for the value.

for example:
```
[
    'secret' => [
        'foo' => 'keepItSecret',
        'bar' => 'tooManySecrets',
    ],
    'algorithm' => [
        'HS256',
    ],
]
```

will become
```
[
    'secret' => [
        'foo' => 'keepItSecret',
        'bar' => 'tooManySecrets',
    ],
    'algorithm' => [
        'foo' => 'HS256',
        'bar' => 'HS256',
    ],
]
```

Updatig the readme to explain whe the KID is now needed when passing
when decodig the token also why the token need the KID to be set in the
header

Make the package conflict with `tuupola/slim-jwt-auth`

Pointing references to this repository