Install and configure eslint and eslint-config-edx (alongside JSHint for now)

scripts/all-tests.sh

@@ -12,7 +12,8 @@ set -e
 
 # Violations thresholds for failing the build
 export PYLINT_THRESHOLD=4175
-export JSHINT_THRESHOLD=7550
+export JSHINT_THRESHOLD=7550  # @TODO Remove, deprecated in favor of ESLint
+export ESLINT_THRESHOLD=49019
 
 SAFELINT_THRESHOLDS=`cat scripts/safelint_thresholds.json`
 export SAFELINT_THRESHOLDS=${SAFELINT_THRESHOLDS//[[:space:]]/}