Bug/Feat: Make tabs Condidtional

[idesignpixels]

Short description of the problem:

In Ionic 2 beta7 and previous.
Tabs template does not work using ngIf or ngSwitch conditions.
It only works when adding a tab but does not remove a tab when condition is false.
If the condition is met more than once multiple instances of the same tab are rendered in the dom.

Steps to reproduce:

1. Start tabs project
2. add ngSwitch/ngIf to tabs template

For example

<ion-tabs tabbarPlacement="bottom" [ngSwitch]="userData.profileRole">
  <ion-tab tabIcon="home" [root]="home"></ion-tab>
  <ion-tab tabIcon="bookmark" [root]="bookmarks"></ion-tab>
  <ion-tab *ngSwitchWhen="'staff'" tabIcon="lock" [root]="admin"></ion-tab>
  <ion-tab tabIcon="settings" [root]="settings"></ion-tab>
</ion-tabs>

[VR-Architect]

Up vote for this bug or feature. For line-of-business applications, use of dynamically added tabs is key. We show/hide based upon permissions areas of a record.

[dylanvdmerwe]

Please see: #5768

This can be accomplished using the show input property on each tab. http://ionicframework.com/docs/v2/api/components/tabs/Tab/#input-properties

[idesignpixels]

Although this is a reasonable ui fix this isn't removing it from the dom but merely hiding it from the user.
Someone can select it from the dom, remove the hidden attribute on the tab and then click it navigating to a page not meant for them.
This is not the solution.

[adamdbradley]

@Lindstrom1989 Using the show input property would be the correct solution. Not having it in the DOM shouldn't matter, and if someone is hacking the DOM to view pages they shouldn't see, those pages should have the correct security on them if it's an issue.