Add retweet button component

Expand API service for retweet

src/components/retweet_button/retweet_button.vue

@@ -0,0 +1,18 @@
+<template>
+  <div>
+    <i :class='classes' class='icon-retweet fa' v-on:click.prevent=''></i>
+    <span v-if='status.repeat_num > 0'>{{status.repeat_num}}</span>
+  </div>
+</template>
+
+<script src="./retweet_button.js" ></script>
+
+<style>
+ .icon-retweet {
+     cursor: pointer
+ }
+ .retweeted {
+     cursor: auto;
+     color: green;
+ }
+</style>