Add .eslintignore file to ignore files containing Jinja templates.
Add .eslintignore file to ignore files containing Jinja templates.

Review-Url: https://chromiumcodereview.appspot.com/2422713002

catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,sahiljain/catapult,sahiljain/catapult,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,benschmaus/catapult,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult