Updated all application urls to allow path prefix.

Allows BookStack to be installed at a non-root location on a domain.
Closes #40.

app/User.php

@@ -160,6 +160,15 @@ class User extends Model implements AuthenticatableContract, CanResetPasswordCon
         return baseUrl('/settings/users/' . $this->id);
     }
 
+    /**
+     * Get the url that links to this user's profile.
+     * @return mixed
+     */
+    public function getProfileUrl()
+    {
+        return baseUrl('/user/' . $this->id);
+    }
+
     /**
      * Get a shortened version of the user's name.
      * @param int $chars