i18n documentation - added note for caching in multi language modules
Revert "Merge pull request #2390 from phptek/2389"

This reverts commit 58da57dd1b6b47d7e2e5a8ab109268bbae8e1c3b, reversing
changes made to 8864256601bb295f8a52ad2eea04c4e1f8087c1b.
Add backwards compatibility for has_extension
Update docblocks
FIX: Use Injector API for managing Member_Validator instance.

Updates the CMS profile page and SecurityAdmin to give developers a few ways to customise the required fields.

Added extension hook updateValidator for getValidator for things like modules to inject required fields to go along with Injector for replacing the entire class for project specific use.
HTML attr encoding for UploadField config

Also fixed UploadField operation with canUpload=false,
which broke the JS because no config could be found,
since the <input> field wasn't present. We can't put the data-config
attribute on the field holder, since fields can be rendered
without their field holder through FormField->SmalLFieldHolder().

Fixes https://github.com/silverstripe/silverstripe-cms/issues/874
array check to ensure getRemoteJoinField() gets an array from Config::inst()->get($remoteClass, 'has_one') (related issue: #2570)
API: DataObject->getRemoteJoinField() no longer defaults to ParentID but throws an exception instead
FIX #2496 `ConfirmedPasswordField` mismatch passwords saved

Fixes #2496

Also fixes another issue where 'Password' is hard coded as field name in `validate()`
Removed deprecated log/email logic from Debug (fixes #2573)

Was deprecated in 2009 with a682ab9c0e211167984b76790fb1458aae7ead7c,
and removed in 2012 with 9eca2d676f9278ba528cb2ea6be4151703ed8fc2
Merge pull request #2575 from dhensby/patch-2

FIX #2496 `ConfirmedPasswordField` mismatch passwords saved
Merge pull request #2526 from clyonsEIS/3.1

Add backwards compatibility for has_extension
Merge pull request #2537 from wilr/membervalidator

FIX: Use Injector API for managing Member_Validator instance.
Merge pull request #2395 from ARNHOE/patch-1

i18n documentation - added note for caching in multi language modules
FIX: Allow TreeDropdownField to open upwards (fixes #2188)
Merge pull request #2589 from kinglozzer/2188-treedropdownfield-overflow

FIX: Allow TreeDropdownField to open upwards (fixes #2188)
API TinyMCE contextmenu is disabled by default

Allows for built-in browser spell-check to be used
Document how to enable TinyMCE context menu

Required since https://github.com/silverstripe/silverstripe-framework/pull/2591
Merge pull request #2591 from colymba/tinymce-contextmenu-off

API TinyMCE contextmenu is disabled by default
Update docs to consistently use http://localhost/ (fixes #1919)