Allow redirection if non vanity provided

[WhiteTomX]

Fixes #464 by redirecting root to configured rootDirectUrl or defaultRedirectUrl (configured as App Settings) or azure.com (hard coded). You need to configure AzureWebJobsDisableHomepage=true to disable the homepage shown at default. This is added to the ARM template.

[FBoucher]

I like your idea @WhiteTomX let see how that will fit in the new design.

[gjbundy]

I implemented this code in my test slot and it works perfectly!