[TASK] Set X-UA-Compatible to IE=9 for Backend

To use the rendering engine of IE9 in the Backend of TYPO3, change the
X-UA-Compatible setting from IE=8 to IE=9.

Change-Id: Ieddd6f5bf2b4aa2e47bd98547d79c83c639ddda4
Resolves: #30664
Releases: 4.7
Reviewed-on: http://review.typo3.org/5632
Reviewed-by: Markus Klein
Reviewed-by: Georg Ringer
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter