[cli] cleanup gen_validator output (Fixes #396)
[cli] cleanup gen_validator output (Fixes #396)

so we can pipe result to a file:

```
tendermint gen_validator > example.json
```

before this we had to cut first 3 lines:

```
tendermint gen_validator | sed 1,3d > example.json
```

tendermint/tendermint,tendermint/tendermint,tendermint/tendermint,tendermint/tendermint