fix documentation for flask-login authentication

Don’t initialize index_view twice

Since #1238 was merged, `index_view` would be initialized twice, which
caused the url of an `index_vew` passed in to `Admin.__init__()` not
being read (causing 404s for me 😢). This PR fixes that.

add flake8 test to travis.yml

Add flake8 to tests

use tox, fix mongoengine & python 2.6 tests

add test for column_filters with sqla obj

fix pymongo example ImportError

prevent column_list from being used for details view

use property name rather than db column name for form_choices

Fixes specifying column filter by instance

Fix mongoengine not prettifying form labels

checking valuelist in process_formdata for Select2TagsField 

add csrf token validation to actions

remove speaklater dependency

fixed loop counter

use loop index instead of explicit increment of column

see http://stackoverflow.com/questions/7537439/how-to-increment-a-variable-on-a-for-loop-in-jinja-template#comment16308022_7537466

Change `data-role` attribute for `Select2TagsWidget`.

image upload field: fixed for change form if file was already uploaded

Prevent <escape> key from confirming deletions

This reverts commit 2e107edc.

This reverts commit 756b9412.