* remove jshint (yihongwang)
 * add .eslintrc and fix errors/warnings (yihongwang)
 * add eslint-env annotation (yhwang)
 * add eslint check in pretest (yhwang)
 * indent with 2 spaces (yhwang)
 * Use regex to test the outcome result (juangmj)
 * Fix the jshint errors (juangmj)
 * Allow users to create their own sandbox object (juangmj)
 * Add the switch policy (juangmj)
 * Add testcases for the condition error in "if" (juangmj)
 * Extract the evaluation logics into a new module "sandbox" (juangmj)
 * Rename the testcases of the operation-switch policy (juangmj)