keep a list of wrapped function names for use in -h output

adds actual commands list to -h output:

```
~/src/ua-api-utils (master)$ ua -h
usage: ua [-h] [-v --verbose] [-o --out OUTFILE] command app_key secret

positional arguments:
  command           command to run
  ...
```
becomes
```
 ~/src/ua-api-utils (help_enhancement)$ ua -h
usage: ua [-h] [-v --verbose] [-o --out OUTFILE] command app_key secret

positional arguments:
  command           command to run [get-tokens, get-apids, get-pins, get-
                    users, get-tags]
  ...
```