API UploadField functions on new records

Fixed regression from 1e5d40474d43ddb0ade22bbf7db5ec494b979fea (UploadField::canPreviewFolder).
Merged in pull request #2009 - (6018bdd631ec98345bba5cd26ef5a29f6f412678).
Merged pull request #1259 (34bfc862eee061ce30998a085aac6170022c3a7e).
Fixed scrutiniser issues
BUG Fixed major issue with testing dataobjects that implement TestOnly and extend non-TestOnly dataobjects. Database regeneration would incorrectly populate the ClassName column
BUG: correct handling of multiple classes
Fixes for LeftAndMain::require_themed_css()

LeftAndMain::require_themed_css() was setting an incorrect property, and a typo meant that those requirements would never be detected anyway
FIX Making path names consistent

I've changed the variables to use the absolute path as the path is unhelpful for debugging and this is more consistent with the other lines of code below
Merge pull request #2024 from kinglozzer/leftandmain-themedcss-fix

Fixes for LeftAndMain::require_themed_css()
Merge pull request #2025 from dhensby/patch-1

FIX Making path names consistent
Merge pull request #2023 from g4b0/left-and-main-classes

BUG: correct handling of multiple classes
Merge branch '3.1-uploadfield-enhancement' of git://github.com/tractorcow/sapphire into tractorcow-3.1-uploadfield-enhancement
Fixed UploadField width (same as textual fields)

Was getting too wide due to padding which isn't applied
to other fields (e.g. TextField)
Merge pull request #2017 from tractorcow/3.1-classname-test-fix

BUG Fixed major issue with testing dataobjects that implement TestOnly
New video formats in allowed_extensions

See https://github.com/silverstripe/silverstripe-installer/pull/41
Improve docs (mostly spelling)
FIX: Add missing 'groupby' and remove redundant conditional in 'having'
Merge pull request #2029 from nedmas/patch-2

FIX: Add missing 'groupby' method
BUGFIX: Removed regression introduced in 9741d1. With the former in place, CMS authors can no longer perform batch publish actions
Merge pull request #2032 from phptek/bug/revert-9741d1

BUGFIX: Removed regression introduced in 9741d1.
NEW: More helpful message for 'sake dev/build' on new envs.

This change alters the no-db message on cli execution to give a bit more of a helpful set-up instruction.
The main motivation for this is so that composer can be set to run dev/build on post-install and post-update.

With that feature added, this will ensure that users installing with composer create-project won't be left
in the dark.

An improvement on this would be a shell script that interactively asked for details to populate this file
with, but one step at a time.
Merge pull request #2033 from sminnee/better-no-db-error

NEW: More helpful message for 'sake dev/build' on new envs.