bash completion for pidcat

I just wrote up a bash completion script, this goes into `/etc/bash_completion.d/` then the next time you launch `/bin/bash`, `pidcat` will have full, interactive completion, including automatic fetching of device serials and package names, i.e.:

```bash
pidcat --serial e [Tab]
pidcat --serial emulator-5554
```

and

```bash
pidcat info.g [Tab]
pidcat info.guardianproject.o [Tab]
pidcat info.guardianproject.otr.app.im
```

Use under whatever free software license you want: (GPL, LGPL, MIT, BSD, Apache, public domain, etc)