Fix test coverage configuration

Author: wanseob

.solcover.js

@@ -1,7 +1,5 @@
 module.exports = {
   norpc: true,
-  testCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle test --network coverage',
-  compileCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle compile --network coverage',
   skipFiles: [
     'contracts/Migrations.sol',
     'contracts/implementation.sol'