Simplify running the WADO Server from Visual Studio

[Zaid-Safadi]

Currently once you clone the DICOMcloud code, you must create a database and update the web.config with the connection string along with the location where the images should be stored.
Also, the code structure which configures the server could be improved for better readability and customization.

This process should be enhanced such that the user can run the server immediately after cloning with no to little configuration

[Zaid-Safadi]

DICOMcloud WebAPI Server can run now immediately after cloning from Visual Studio 2015 as a standalone DICOMweb server with no additional configuration:

Solution proposed in this commit:

1. Provide default value for image storage location in the web.config:
   <add key="app:PacsStorageConnection" value="|DataDirectory|\App_Data\Storage\ds" />

The server code now supports using the variable "|DataDirectory|" when reading the app:PacsStorageConnection which resolves to the .NET Environment.SpecialFolder.ApplicationData directory

2. Database is attached to LocalDB installed with Visual Studio by setting a default value for the app:PacsDataArchieve (connectionString) in the web.config:
   <add key="app:PacsDataArchieve" value="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\DB\DICOMcloud.mdf;Initial Catalog=DICOMcloud;Integrated Security=True" />

A DICOMcloud.mdf database file is added under the Resources\Database directory and is copied (only if newer) to the App_Data folder during project built. This DB is attached to the local SQL Instance installed with Visual Studio 2015 using the default connection string.

3. The code which configure the DICOMcloud WebAPI server has been refactored in this class DICOMBuilder.cs and is structured in a way that allows inheritance and customization