autocomplete: use select2 when selecting users or groups to give permissions This is a minimal change to MembersAutoComplete, inspired by Dominik Ruf. The UX is slightly different than before, with select2 putting up an extra input field, already before typing anything. We use minimumInputLength 1 to get the same behaviour as before and avoid displaying all users in a list.

[pytest]
# only look for tests in kallithea/tests
python_files = kallithea/tests/**/test_*.py
addopts =
    # --verbose
    # show extra test summary info as specified by chars (f)ailed, (E)error, (s)skipped, (x)failed, (X)passed, (w)warnings.
    -rfEsxXw
    # Shorter scrollbacks; less stuff to scroll through
    --tb=short