Folder structure

Rearranged the folder structure. This change doesn't change any program logic, just moves the files (and namespaces) around so that the layout better reflects recent changes.
 
Api wrapper has the following main folders here: 
- Environment - just 2 classes used for reading dependencies and dtos 
- Exceptions. That. Not changed 
- Extensions. Not changed. 
- Http - the HttpClientMediator and closely associated interface & enum 
- Requests - The Request class and all the code for building requests  
- Responses - the Response class, and all the code for parsing and caching responses  

It's not a perfect layout but IMHO it's a lot simpler and closer to the current design