Guillotina 5 compatibility + bugfixes

Merge pull request #16 from onna/search-attr

- Support searching on multiple attributes

2.0.4: Merge pull request #11 from onna/error-response

- Handle auth validation errors gracefully

2.0.3: Merge pull request #8 from onna/first-last-name

Support first/last name in add_user

1.1.18: Merge pull request #9 from onna/first-last-1x

Support first/last name

2.0.1: Merge pull request #6 from onna/fixes

aiohttp 3.4 fixes