Expose login component setting in app.config

[binduwavell]

Have been discussing this with Denys.

The login component has a bunch of configuration https://github.com/Alfresco/alfresco-ng2-components/blob/develop/docs/core/components/login.component.md#custom-logo-and-background

In ACA these values are hard coded and can't be set in app.config.

We would like these settings to be configurable in ADW:

• backgroundImageUrl
• logoImageUrl

These look like they would also be helpful:

• needHelpLink
• registerLink
• showRememberMe