api: add chroots to playground api call
Automatic commit of package [copr-frontend] release [1.33-1].
[frontend] SEND_EMAILS config correction
correctly print chroots

addressing:

Exception on /api/playground/list/ [GET]
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1687, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1360, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1358, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/lib/python2.7/site-packages/flask/app.py", line 1344, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/share/copr/coprs_frontend/coprs/views/api_ns/api_general.py", line 467, in playground_list
    jsonout = flask.jsonify(output)
  File "/usr/lib/python2.7/site-packages/flask/helpers.py", line 198, in jsonify
    indent=None if request.is_xhr else 2), mimetype='application/json')
  File "/usr/lib64/python2.7/json/__init__.py", line 250, in dumps
    sort_keys=sort_keys, **kw).encode(obj)
  File "/usr/lib64/python2.7/json/encoder.py", line 209, in encode
    chunks = list(chunks)
  File "/usr/lib64/python2.7/json/encoder.py", line 434, in _iterencode
    for chunk in _iterencode_dict(o, _current_indent_level):
  File "/usr/lib64/python2.7/json/encoder.py", line 408, in _iterencode_dict
    for chunk in chunks:
  File "/usr/lib64/python2.7/json/encoder.py", line 332, in _iterencode_list
    for chunk in chunks:
  File "/usr/lib64/python2.7/json/encoder.py", line 408, in _iterencode_dict
    for chunk in chunks:
  File "/usr/lib64/python2.7/json/encoder.py", line 332, in _iterencode_list
    for chunk in chunks:
  File "/usr/lib64/python2.7/json/encoder.py", line 442, in _iterencode
    o = _default(o)
  File "/usr/lib64/python2.7/json/encoder.py", line 184, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <coprs.models.MockChroot object at 0x7f9ef4c72450> is not JSON serializable
copr-cli cancel fix