Fixed numerous issues in pyro.sort_tree

Fixed numerous issues in pyro.sort_tree, including:
- user defined classes (like 'no-nest') were being removed
- wrong icons were being set for all parents when dragging items with hidden children
- child icons didn't properly update when dragging/dropping items with children
- cookies weren't saved when dragging/dropping items
- cookies could save invalid states
Better styling on the database selection area on step1 of installer.
Call events based on namespace_slug.stream.stream_slug.event.saved
Even better
Updated windows platforms

Added Windows 7,8 and 8.1, also modified Longhorn to Vista.
This was stupid
Not good - could easily be singular if name is plural - bad - naughty
Follow lang convention
Use text instead of binary
Cover string type relation IDs too like files
Nullable date time for updated_at columns
Consolidate date formats and column names
We had some unix timestamps and some datetime fields, some called created_at and some called created_on. Now its all datetime, created_at (non-null) and updated_at (nullable).
Ran PSR-2 CS Fixer.
Slug field type was unable to find related fields
Fixed for PSR-2 CS "fixes"
These are site ref generated models. Should not be committed. They get regenerated when streams are updated.
Fix duplicating pages
Bumped 2.3 requirements to 5.3.9.
Merge branch '2.3/develop' of https://github.com/pyrocms/pyrocms into 2.3/develop
PHP CS Fixes for PSR-2 in installer.