fix bug with player not getting updated on disconnect (related to issue #24)

jint version downgraded for better stability (also locked the engine instance as it's not thread safe)
updated readme
remove vpn detection from application configuration as it's now in a seperate plugin
defaulted webfront bind URl to all interfaces
readd the custom say name
added visibility percentage to AC

SharedLibraryCore/Migrations/DatabaseContextModelSnapshot.cs

@@ -111,6 +111,8 @@ namespace SharedLibraryCore.Migrations
 
                     b.Property<int?>("ViewAnglesVector3Id");
 
+                    b.Property<double>("VisibilityPercentage");
+
                     b.Property<int>("Weapon");
 
                     b.Property<DateTime>("When");