add json support to SQLA backend

Add default type formatters for Enum

Fix typo

List row actions

Allow flipping mapbox coordinates to/from db

remove unnecessary indention in form.py convert

Fixed bugs

fix hybrid_property TypeError introduced by #1209

SQLA - fix hybrid property support after column object support changes

Fixed broken link to tablib readme

Geo widget doesn't work by https #1234

Test python 3.5 on travisci, and use coveralls and pylint.

Support Python 3.5

The current Leaflet implementation expects coordinates in latitude-longitude order but GeoJSON and PostGIS works the other way around with lng first. These changes work around this behavior by passing the data to and from db through PostGIS’s `ST_FlipCoordinates` function if the setting `MAPBOX_FIX_POINT_COORDINATES` is something truthy. This is to not break the current behavior. Right now a warning is emitted when this setting hasn’t been enabled but I would recommend to remove this setting and make its behavior the default in the next major version.

Fix missing code in docstrings