BUG: Fixed out of date RFC 4180 URL

BUG: Fixed out of date RFC 4180 URL
Injector updateSpec() instanciation (fixes #2829)
cs_CZ transliteration chars (fixes #2816)
Merge pull request #2821 from silverstripe-rebelalliance/rfc4180

BUG: Fixed out of date RFC 4180 URL
Updated add-on URL.
Use filtered file paths in upload (fixes #2836)
Merge pull request #2834 from mattkirwan/patch-1

Updated add-on URL.
Correct JS i18n in UploadField (fixes #2370)
NEW: Forms with invalid/expired SecurityIDs are repopulated (fixes #1891)
BUG Fix missing description element on FieldGroup_holder.ss
Merge pull request #2839 from tractorcow/pulls/3.1-fieldgroup-description

BUG Fix missing Description element on FieldGroup_holder.ss
Fixing SQLQueryTest failures on PHPUnit 3.7.30
Merge pull request #2837 from chillu/pulls/2836-upload-filename-filter

Use filtered file paths in upload (fixes #2836)
Fixed and documented SS_Datetime methods that returned formatted date/times.
Merge pull request #2840 from yearofthegus/document-datetime

Fixed and documented SS_Datetime methods that returned date and/or time
Merge pull request #2835 from kinglozzer/1891-csrf-friendly-error

NEW: Forms with invalid/expired SecurityIDs are repopulated (fixes #1891)
Merge branch '3.1'