Add ability to customize internal HttpClient

[Arcalise08]

In a situation personally in which I need to directly modify the HttpClient being used in this library. So I added the ability to pass in an HttpClient to the UI options, which is used for the lifetime of the application.

[update-docs]

Thanks for opening this pull request! If you have implemented new functions, write about them in the readme file.

[Burgyn]

Hey,

thanks for the PR. The idea is good for me, but I don't like the implementation. I don't want to allow the HttpClient to be entered directly (not good practice). I'd rather just add the ClientName and let the factory create the correct client based on that.

[Arcalise08]

I have made the requested changes. I accidently pushed a version change with this which we can rollback if you like. I also noticed that this package doesnt include <GenerateDocumentationFile>true</GenerateDocumentationFile> . I wasnt sure if that was something you had set locally as i cant get comments to show up once packed without it. But other then that I hope this meets your expectations.

[Arcalise08]

Sorry about the extra commits. I really shouldnt push changes before my morning coffee

[Burgyn]

Thanks a lot.

Your changes will be release soon as version 6.1.0 .

[Burgyn]

Sorry, 6.2.0 of course.