Add solcover configuration

Author: wanseob

.solcover.js

@@ -0,0 +1,9 @@
+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'
+  ]
+}