Fix problem with hard-coded shebang in ipa command line tool by using
a proper setuptools entry point for the console script. ipaclient is now
an executable Python package, too.
```
$ python -m ipaclient ping
```
is equivalent to
```
$ ipa ping
```
Related: https://pagure.io/freeipa/issue/6653
Closes: https://pagure.io/freeipa/issue/6850
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Tomas Krizek <tkrizek@redhat.com>
