Fixed issues #26, #31, #33 where running multiple instances cause var…

[JimiC]

…ious exceptions to be thrown.

[JimiC]

1. Fixed Exception #26 by adding exception handler and debug logger when UnauthorizedAccessException is thrown.
2. Fixed Exception on Start() #31 by modifying the 'Save' logic to not be asynchronous, in order for the settings to get saved before the process exits, avoiding creating malformed CSharpAnalytics-MeasurementQueue file.
3. Fixed Starting multiple instances of a WPF application at same time throws Exception in Start() #33 by modifying the 'Save' logic to not be asynchronous, avoiding thread race between multiple instances.

@damieng In the process of fixing the issues I changed the way the library saves and reads the storage files. Used XmlWriter in order to produce a line intended file which makes it more readable. If this is an issue please let me know so to revert those changes.

[damieng]

I suspect this changes the underlying format? If so then this change causes all clients to use their current information and be treated as new users again :(

[JimiC]

In matter of fact it doesn't change anything regarding the data. The previous format was a non-intended xml and by using XmlWriterSettings it produces an intended xml. The serializer (DataContractSerializer) didn't changed thus the objects get serialized and deserialized as before.