getSite(shortName) gets a site for a provided short
      name.
  
    Parameters
- shortName
 - The short name of the site
 
Returns
Return a site object, or returns null if the site does not exist.
Example
var site = siteService.getSite("simple-site");
if(site){
    
    model.sitePreset = site.sitePreset;
    model.shortName = site.shortName;
    model.title = site.title;
    model.description = site.description;
}