fix(adapter): fix windows json editing

The json parsing that we were using was overly complicated. This is much simpler and solves some of
the odd behavior that was happening on windows when installing and dealing with adapters.

Closes #42

package.json

@@ -63,7 +63,6 @@
     "gulp": "3.9.0",
     "gulp-git": "1.6.0",
     "inquirer": "0.11.0",
-    "json": "9.0.3",
     "minimist": "1.2.0",
     "node-uuid": "1.4.3",
     "nodemon": "1.8.1",

src/commitizen/adapter.js

@@ -1,6 +1,7 @@
 import path from 'path';
 import fs from 'fs';
 import findNodeModules from 'find-node-modules';
+import _ from 'lodash';
 
 import {isFunction} from '../common/util';
 
@@ -28,8 +29,23 @@ export {
  * Must be passed an absolute path to the cli's root
  */
 function addPathToAdapterConfig(sh, cliPath, repoPath, adapterNpmName) {
+
+  let commitizenAdapterConfig = {
+    config: {
+      commitizen: {
+        path: `./node_modules/${adapterNpmName}`
+      }
+    }
+  };
+
   let packageJsonPath = path.join(getNearestProjectRootDirectory(), 'package.json');
-  sh.exec(`${cliPath}/node_modules/.bin/json -I -f ${packageJsonPath} -e 'if(!this.config) {this.config={};}; if(!this.config.commitizen) { this.config.commitizen={};}; this.config.commitizen.path=\"./node_modules/${adapterNpmName}\"'`);
+  let packageJsonString = fs.readFileSync(packageJsonPath);
+  let packageJsonContent = JSON.parse(packageJsonString);
+  let newPackageJsonContent = '';
+  if(_.get(packageJsonContent,'config.commitizen.path') !== adapterNpmName) {
+    newPackageJsonContent = _.merge(packageJsonContent, commitizenAdapterConfig);
+  }
+  fs.writeFileSync(packageJsonPath, JSON.stringify(newPackageJsonContent));
 }
 
 /**