Added lib.security.password lib

no issue

- move password hashing and password comparison to lib/security/password
- added two unit test
- FYI: password hashing takes ~100ms
  - we could probably mock password hashing in certain cases when unit testing

ghost/security/lib/index.js

@@ -15,5 +15,9 @@ module.exports = {
 
     get identifier() {
         return require('./identifier');
+    },
+
+    get password() {
+        return require('./password');
     }
 };

ghost/security/lib/password.js

@@ -0,0 +1,18 @@
+'use strict';
+
+module.exports.hash = function hash(plainPassword) {
+    const bcrypt = require('bcryptjs'),
+        bcryptGenSalt = Promise.promisify(bcrypt.genSalt),
+        bcryptHash = Promise.promisify(bcrypt.hash);
+
+    return bcryptGenSalt().then(function (salt) {
+        return bcryptHash(plainPassword, salt);
+    });
+};
+
+module.exports.compare = function compare(plainPassword, hashedPassword) {
+    const bcrypt = require('bcryptjs'),
+        bcryptCompare = Promise.promisify(bcrypt.compare);
+
+    return bcryptCompare(plainPassword, hashedPassword);
+};