Make compatible with latest mongoengine.

sqla ajax loader - prevent error when primary key name != attribute name

Add nowrap to action icons table cell

This was added in the past to the bootstrap2 css but not to the bootstrap3 css.

Update layout_bootstrap3 readme paths

The paths in this readme were no longer correct.

remove unnecessary DateTimeField imports

Fix DeprecationWarning

prevent validators from getting inserted twice

add form blocks to modal and fileadmin templates too

Add block form on edit and create templates

FileAdmin - alert user when upload fails due to file already existing

Do not disclose the file system full path

Update base.py

Fix & test for #988: column_filters in not compatible with babel.

Remove Flask-SQLAlchemy dependency

It should be noted that the declarative base still has to be configured
like this:

```python
MyBase:
    query = session.query_property()
```

Also decreased code duplication and removed unused imports.

For example, when uploading a file called "foo/bar.txt" twice, right now it shows the full directory (e.g., "File /your/system/directory/foo/bar.txt already exists"), instead of only showing "File foo/bar.txt already exists".

flask_admin/model/base.py:949: DeprecationWarning: Required is going away in WTForms 3.0, use DataRequired
(though in this case, I believe the correct choice is InputRequired, though that only matter if an object has id=0)

Added placeholder methods for calling functions before deletion

improve error message when resolve_ctx is missing

Use WTForms translations for (non-custom) validation errors