fix greater/smaller filters for pymongo

Fix incorrect usage of NotImplemented constant

`NotImplemented` is a constant singleton used in rich comparison
overloading. It is not callable, and is not an exception.
`NotImplementedError` is a built in exception.

WTForms 2 compatibility

Replaced deprecated TextField with StringField

Typo fix in form_rules.rst

IE8 filters compatibility

Use child icon in menu macro

Standardise Examples

filter never worked, because value is passed as string and mongodb returns zero documents

Update Bootstrap info

See "New license" section of http://blog.getbootstrap.com/2014/01/30/bootstrap-3-1-0-released/
and https://github.com/twbs/bootstrap/blob/master/LICENSE

See http://getbootstrap.com/about/#brand

Fix rendering in IE9

glyphicon-remove instead of icon-remove in bs3 template

Outerjoin searches

Unless we do this, any record not being referenced by all child
relations will get excluded from the search.

JOINing together all the relations excludes all records without children
from the search.

Add import for Baseview and expose to baseview doc

issue #636

Exception: Unsupported filter type (tinyint)

Add documentation for import for required()