Fix error formatting "count" results

Hi math campers (what does that mean?), thanks for dql, it is really cool and useful!  While trying it out I was getting this error when running the `count` command, which is fixed in this PR.

```
us-east-1> count test_Rollups WHERE key = 'XXXX';
Traceback (most recent call last):
  File "/home/cce/dql.env/lib/python2.7/site-packages/dql/cli.py", line 120, in start
    self.cmdloop()
  File "/usr/lib/python2.7/cmd.py", line 142, in cmdloop
    stop = self.onecmd(line)
  File "/usr/lib/python2.7/cmd.py", line 220, in onecmd
    return self.default(line)
  File "/home/cce/dql.env/lib/python2.7/site-packages/dql/cli.py", line 313, in default
    self._run_cmd(command)
  File "/home/cce/dql.env/lib/python2.7/site-packages/dql/cli.py", line 324, in _run_cmd
    has_more = self.formatter.write(results, ostream)
  File "/home/cce/dql.env/lib/python2.7/site-packages/dql/output.py", line 91, in write
    for result in results:
TypeError: 'int' object is not iterable
```