Fixed issue with constructing query with joins at sqlalchemy ModelView

Add basic tests for SQLAlchemy inlineform implementation

Add form field for tags and PostgreSQL ARRAY field support

Fixed #83. Incompatible change - if you overriden create_form/edit_form in your views, remove from from the parameters

Improve docs on how to use custom InlineFormAdmin for inline_models

s/Chosen/Select2

See https://github.com/ivaynberg/select2/issues/426

Select2 is relatively more advanced compared to Chosen.

Select2 is distributed under Apache License, Version 2.0

Defining flask_admin.__version__ and use it where appropriate

Don't override query_factory if passed in form_args

Fix file uploads in edit form

I've removed explicit `request.form` passing to edit form in the form instance
creation. The reason for this is that if we pass `formdata` to the constructor
it considers that all the data it needs, whilst `request.form` contains no
information about uploaded files.

If we simply omit passing `request.form` around, Flask-WTF takes care about
filling the form with `request.form` as well as `request.files`, if there are
any.

Hence file uploads now work in the model edit.