Perf improvement: add partial-search implementation

TL;DR: Still needs tests before we will merge, but if you're in need of a serious perf boost right, I can vouch that this patch seems stable in our production env.

fixes #25.

On a meager 300 nodes it was much faster faster.

via rest:

```
real	0m22.518s
user	0m0.000s
sys	0m0.020s
```

via partial search:

```
real	0m3.320s
user	0m0.008s
sys	0m0.008s
```

To get the tests (and thus partial search) accepted upstream, I'll need to test from the api call to the http request, and http response back to returned values. This will take a bit.

- [x] proof of concept implementation
- [ ] unit tests
- [ ] better short flag than `-q` for `--use-partial-search`