AppSettingsReader
The AppSettingsReader class provides a wrapper for System.Configuration.ConfigurationManager.AppSettings
which provides a single method for reading values from the config file of a particular type.
public AppSettingsReader()
Gets the value for specified key from ConfigurationManager.AppSettings, and returns
an object of the specified type containing the value from the config file. If the key
isn't in the config file, or if it is not a valid value for the given type, it will
throw an exception with a descriptive message so the user can make the appropriate
change