[C#][NancyFX] Better "Add" for Dictionary and using {{packageName}} for NancyFX

[wing328]

• use square bucket for Dictionary add (performance improvement)
• use {{packageName}} instead of {{packageTitle}} for C# NancyFX generator: [C#] RootNamespace/AssemblyName use packageName #3442
• use debug instead of info for some log entries in C# NancyFX generator (for cleaner output)