Fix getPosition

* Re adds the v1 endpoint as `getPositions`
* Fixes params for v2 endpoint `getPosition`

Resolves: #5

lib/rest-client.js

@@ -109,8 +109,15 @@ module.exports = class RestClient {
     return await this.request.post('/user/leverage/save', params);
   }
 
-  async getPosition() {
-    return await this.request.get('/v2/private/position/list');
+  async getPosition(params) {
+    assert(params, 'No params passed');
+    assert(params.symbol, 'Parameter symbol is required');
+
+    return await this.request.get('/v2/private/position/list', params);
+  }
+
+  async getPositions() {
+    return await this.request.get('/position/list');
   }
 
   async changePositionMargin(params) {