message: feat(demo): opportunity to change bs theme by url query
diff: +import { ActivatedRoute, NavigationEnd, Router } from '@angular/router';
  import { Component, Inject, OnDestroy, Renderer } from '@angular/core';
  -import { NavigationEnd, Router } from '@angular/router';
  +import { DOCUMENT } from '@angular/common';
  +
  import { isBs3, setTheme } from 'ngx-bootstrap/utils';
  import { routes } from '../../app.routing';
  import { StyleManager } from '../../theme/style-manager';
  import { ThemeStorage } from '../../theme/theme-storage';
  -import { DOCUMENT } from '@angular/common';
  +
  import { Subscription } from 'rxjs';
  const _bs3Css = 'assets/css/bootstrap-3.3.7/css/bootstrap.min.css';
  @@ -28,13 +30,15 @@ export class SidebarComponent implements OnDestroy {
  scrollSubscription: Subscription;
  constructor(
  - public styleManager: StyleManager,
  + private activatedRoute: ActivatedRoute,
  + private renderer: Renderer,
  private router: Router,
  private themeStorage: ThemeStorage,
  - private renderer: Renderer,
  + public styleManager: StyleManager,
  @Inject(DOCUMENT) private document: any
  ) {
  - const currentTheme = this.themeStorage.getStoredTheme();
  + const themeFromUrl = this.activatedRoute.snapshot.queryParams._bsVersion;
  + const currentTheme = themeFromUrl || this.themeStorage.getStoredTheme();
  if (currentTheme) {
  this.installTheme(currentTheme);
  }
  