Namespace Heka Utility Applications

@RaFromBRC

Namespace heka utilities with a namespace prefix of heka- to match heka-inject.

This does not address the auto-completion of the hekad binary. I think a reasonable approach would be to recast the hekad binary as just `heka` but there are many touch points for that. If you did this then auto-completion would by default stop at the daemon binary.