Remove params

It drags in a ton of dependencies and can be trivially rewritten with
`url`.

```
$ cargo update -p params
    Removing autocfg v0.1.7
    Removing bodyparser v0.8.0
    Removing buf_redux v0.6.3
    Removing mime_guess v1.8.8
    Removing multipart v0.13.6
    Removing num v0.1.42
    Removing num-bigint v0.1.44
    Removing num-complex v0.1.43
    Removing num-iter v0.1.40
    Removing num-rational v0.1.42
    Removing params v0.8.0
    Removing persistent v0.4.0
    Removing phf_codegen v0.7.24
    Removing phf_generator v0.7.24
    Removing rand v0.6.5
    Removing rand_chacha v0.1.1
    Removing rand_hc v0.1.0
    Removing rand_isaac v0.1.1
    Removing rand_jitter v0.1.4
    Removing rand_os v0.1.3
    Removing rand_pcg v0.1.2
    Removing rand_xorshift v0.1.1
    Removing tempdir v0.3.7
    Removing twoway v0.1.8
    Removing urlencoded v0.6.0
```

Author: jyn514