allow aliasing

Once the service is up and running it is cumbersome to remember urls that have lots of metadata in them. If the arguments are common enough, a user should be able to alias them.

For example a long request like:

```
/setup/slave/?token=sometoken&name=trusty&executors=2
```

Should allow a user to alias it to:

```
/setup/trusty_slave/
```

Special care should be taken care of name collisions (or maybe consider a different endpoint)

Start by tracing the existing /setup/slave/ endpoint and how its token, name, and executors arguments are handled. Define and test alias resolution for /setup/trusty_slave/, including the expected behavior when an alias collides with another name or endpoint.

Written by the indexing model from the issue text.