chore(travis): enable Firefox again

This updates karma-sauce-launcher plugin, which fixes the issue we were having (it uses the latest version of wd).

This reverts 1c18c93

Author: vojtajina

package.json

@@ -25,7 +25,7 @@
     "karma-firefox-launcher": "~0.1.0",
     "karma-ng-scenario": "~0.1.0",
     "karma-junit-reporter": "git://github.com/karma-runner/karma-junit-reporter#karma-0.11",
-    "karma-sauce-launcher": "~0.1.0",
+    "karma-sauce-launcher": "~0.1.1",
     "karma-script-launcher": "~0.1.0",
     "yaml-js": "~0.0.8",
     "marked": "~0.2.9",

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_IE_8,SL_IE_9,SL_IE_10 \
+  --browsers SL_Chrome,SL_Safari,SL_Firefox,SL_IE_8,SL_IE_9,SL_IE_10 \
   --e2e-browsers SL_Chrome