Update Flow to 0.14

Fixes issue with fs.readFileSync return type
See: https://github.com/facebook/flow/issues/416
https://github.com/facebook/flow/compare/v0.13.1...v0.14.0

package.json

@@ -39,7 +39,7 @@
     "eslint": "^0.24.0",
     "eslint-plugin-flowtype": "^1.0.0",
     "eventemitter2": "^0.4.14",
-    "flow-bin": "^0.13.1",
+    "flow-bin": "^0.14",
     "gulp": "~3.8.10",
     "gulp-bump": "~0.1.13",
     "gulp-rename": "~1.2.0",

src/api/common/schema-validator.js

@@ -20,8 +20,7 @@ function isValidLedgerHash(ledgerHash) {
 
 function loadSchema(filepath: string): {} {
   try {
-    const schemaContent: any = fs.readFileSync(filepath, 'utf8');
-    return JSON.parse(schemaContent);
+    return JSON.parse(fs.readFileSync(filepath, 'utf8'));
   } catch (e) {
     throw new Error('Failed to parse schema: ' + filepath);
   }