refractor: shell (#287)

* Refractor components.
* Shift theme picker component to shared module.
* Shift progress bar service into its own folder.
* Add footer to app shell.
* Replace mat-icon by font-awesome icons.
* Fix sidenav visibility bug for handsets.
* Add comments.

Closes #286, Fixes #285

src/app/shared/theme-picker/theme-picker.component.html

@@ -0,0 +1,17 @@
+<button mat-icon-button [matMenuTriggerFor]="themeMenu" matTooltip="Color Schemes">
+  <fa-icon icon="fill-drip" size="lg"></fa-icon>
+</button>
+
+<mat-menu class="mifosx-theme-picker-menu" #themeMenu="matMenu" x-position="before">
+  <mat-grid-list cols="2">
+    <mat-grid-tile *ngFor="let theme of themes">
+      <div mat-menu-item (click)="installTheme(theme)">
+        <div class="mifosx-theme-picker-swatch">
+          <fa-icon class="mifosx-theme-chosen-icon" *ngIf="currentTheme.href === theme.href" icon="check-circle" size="lg"></fa-icon>
+          <div class="mifosx-theme-picker-primary" [style.background]="theme.primary"></div>
+          <div class="mifosx-theme-picker-accent" [style.background]="theme.accent"></div>
+        </div>
+      </div>
+    </mat-grid-tile>
+  </mat-grid-list>
+</mat-menu>