chore(travis): add IE 11 (SL) to the build

Author: vojtajina

travis_build.sh

@@ -5,5 +5,5 @@ set -e
 export SAUCE_ACCESS_KEY=`echo $SAUCE_ACCESS_KEY | rev`
 
 grunt parallel:travis --reporters dots \
-  --browsers SL_Chrome,SL_Safari,SL_Firefox,SL_IE_8,SL_IE_9,SL_IE_10 \
+  --browsers SL_Chrome,SL_Safari,SL_Firefox,SL_IE_8,SL_IE_9,SL_IE_10,SL_IE_11 \
   --e2e-browsers SL_Chrome