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".

Added placeholder methods for calling functions before deletion

improve error message when resolve_ctx is missing

Use WTForms translations for (non-custom) validation errors

fix backwards compat issue with form rules + flask.ext.admin

lock flask-login to 0.2.11 until flask-security is fixed

Update base.py - Typing error

A simple typing error (which can create some misunderstanding if we read the code too fast).

fix build errors caused by pillow

CSV Documentation: fix max rows attribute name

Corrections/tweaks for docs

Revert "Make QuerySelectMultipleField fields editable on the list view"

Make QuerySelectMultipleField fields editable on the list view

For QuerySelectField and ModelSelectField, a select data-type is used.
This element does not support select multiple, but the checklist element
does. The same code for compiling the choices is used.

Change export_max_rows default to unlimited