feat: add app shell (angular-material)

Add app shell built using angular-material and flex-layout. Refractor
code due to configuration changes.

Fixes #52

src/app/accounting/accounting.component.ts

@@ -1,7 +1,7 @@
 import { Component, OnInit } from '@angular/core';
 
 @Component({
-  selector: 'app-accounting',
+  selector: 'mifosx-accounting',
   templateUrl: './accounting.component.html',
   styleUrls: ['./accounting.component.scss']
 })