improvement(vuehorizontaltimeline): adds Scoped Slot compatibility

As of vue 2.6.0, the recommended way to scope slots is by passing data up from the child component.
By binding each item of the iteration, we can access specific data about that item in our slot
template.

src/components/VueHorizontalTimeline.vue

@@ -4,7 +4,7 @@
       <ol>
         <li v-for="(item, i) in items" :key="i" :style="setLineColor">
           <div class="time" :class="getTimeClass(item)" :style="getTimeStyles" @click="cardClicked(item)">
-            <slot v-if="hasSlot"/>
+            <slot v-if="hasSlot" v-bind:item="item"/>
             <span
               class="title"
               v-if="!hasSlot && item[titleAttr]"