restructure presentation layer

- Move most GUI related code to /presentation
- Move components to /components (separate from bootstrap and style)
- Move shared components helpers to /components/shared
- Rename Bootstrapping to bootstrapping to enforce same naming
  convention in /presentation

src/presentation/components/TheFooter/DownloadUrlListItem.vue

@@ -0,0 +1,81 @@
+<template>
+  <span class="url">
+    <a :href="downloadUrl"
+        v-bind:class="{
+            'url__active': hasCurrentOsDesktopVersion && isCurrentOs,
+            'url__inactive': hasCurrentOsDesktopVersion && !isCurrentOs,
+            }">{{ operatingSystemName }}</a>
+  </span>
+</template>
+
+<script lang="ts">
+import { Component, Prop, Watch, Vue } from 'vue-property-decorator';
+import { Environment } from '@/application/Environment/Environment';
+import { OperatingSystem } from '@/domain/OperatingSystem';
+import { ApplicationFactory } from '@/application/ApplicationFactory';
+
+@Component
+export default class DownloadUrlListItem extends Vue {
+  @Prop() public operatingSystem!: OperatingSystem;
+
+  public downloadUrl: string = '';
+  public operatingSystemName: string = '';
+  public isCurrentOs: boolean = false;
+  public hasCurrentOsDesktopVersion: boolean = false;
+
+  public async mounted() {
+      await this.onOperatingSystemChangedAsync(this.operatingSystem);
+  }
+
+  @Watch('operatingSystem')
+  public async onOperatingSystemChangedAsync(os: OperatingSystem) {
+    const currentOs = Environment.CurrentEnvironment.os;
+    this.isCurrentOs = os === currentOs;
+    this.downloadUrl = await this.getDownloadUrlAsync(os);
+    this.operatingSystemName = getOperatingSystemName(os);
+    this.hasCurrentOsDesktopVersion = hasDesktopVersion(currentOs);
+  }
+
+  private async getDownloadUrlAsync(os: OperatingSystem): Promise<string> {
+    const context = await ApplicationFactory.Current.getAppAsync();
+    return context.info.getDownloadUrl(os);
+  }
+}
+
+function hasDesktopVersion(os: OperatingSystem): boolean {
+    return os === OperatingSystem.Windows
+        || os === OperatingSystem.Linux
+        || os === OperatingSystem.macOS;
+}
+
+function getOperatingSystemName(os: OperatingSystem): string {
+    switch (os) {
+        case OperatingSystem.Linux:
+            return 'Linux';
+        case OperatingSystem.macOS:
+            return 'macOS';
+        case OperatingSystem.Windows:
+            return 'Windows';
+        default:
+            throw new Error(`Unsupported os: ${OperatingSystem[os]}`);
+    }
+}
+
+</script>
+
+<style scoped lang="scss">
+.url {
+    &__active {
+        font-size: 1em;
+    }
+    &__inactive {
+        font-size: 0.70em;
+    }
+    a {
+        color:inherit;
+        &:hover {
+            opacity: 0.8;
+        }
+    }
+}
+</style>