FIX Allow Director::$rules like //$Action

In 3.0, doing $Action => SomeController would redirect all action requests
to that default controller. In 3.1, you need to do //$Action => SomeController
but it didnt work - those initial slashes broke matching
Merge pull request #1816 from silverstripe-rebelalliance/bug/emptyrules

FIX Allow Director::$rules like //$Action
Formatting tweaks, fixes silverstripe/silverstripe-cms#641
Auth
Replace logout button with a more commonly used symbol

* Power icon swapped for door icon
* Minor hover/focus opacity effect added to button
Merge pull request #2004 from adrexia/logout-button

Replace logout button with a more commonly used symbol
Fix return the member ID for logInWithPermission

Will now return the ID, as per the doc-block comment
Merge pull request #2006 from ss23/patch-4

Fix return the member ID for logInWithPermission
Merge pull request #2003 from edlinklater/641-insert_link_styling

Formatting tweaks, fixes silverstripe/silverstripe-cms#641
BUG: Display of AssetUpload upload fields

* Replaced file upload icon
* Fixed padding
* Replaced width of droparea with min-width
Merge pull request #2001 from adrexia/asset-upload

BUG: Display of AssetUpload upload fields
Merge branch '3.1' of git://github.com/silverstripe/silverstripe-framework into 3.1
NEW 'Choose another file' button on upload field AAS-917