Update version to 3.0.0

- use MP3 instead of WAV
 - new callbacks & properties
 - refactoring

src/components/downloader.vue

@@ -0,0 +1,37 @@
+<style lang="scss">
+  @import '../scss/icons';
+</style>
+
+<template>
+  <icon-button
+    id="download"
+    class="ar-icon ar-icon__xs ar-icon--no-border"
+    name="download"
+    @click.native="download"/>
+</template>
+
+<script>
+  import IconButton from './icon-button'
+
+  export default {
+    props: {
+      record    : { type: Object },
+      filename  : { type: String }
+    },
+    components: {
+      IconButton
+    },
+    methods: {
+      download () {
+        if (!this.record.url) {
+          return
+        }
+
+        const link = document.createElement('a')
+        link.href = this.record.url
+        link.download = `${this.filename}.mp3`
+        link.click()
+      }
+    }
+  }
+</script>