GitLab

```
verifying github.com/ipfs/go-datastore@v0.0.1/go.mod: checksum mismatch
        downloaded: h1:bYmHO9fuKO1Ca7dpdDBWQl0mndy5b0HFqSJjGlNYtzs=
        go.sum:     h1:d4KVXhMt913cLBEI/PXAy6ko+W7e9AhyAKBGh803qeE=
```

```
verifying github.com/ipfs/go-datastore@v0.0.1: checksum mismatch
        downloaded: h1:u3lrOIBAhGS5prBa94V89LJNMWlEsO2+zgFlEGTl0E4=
        go.sum:     h1:AW/KZCScnBWlSb5JbnEnLKFWXL224LBEh/9KXXOrUms=
```

* Add IpfsDHT.{Bootstrap{Random,Self},Peer{Id,Key}}
* Include client mode tests, support for Ping, and uncruft setupDHTs
* Include xerrors in deps

This reverts commit 7e68ac3c.

Fixes race conditions in the tests when using go modules.