Done implementing API validation.

Installer validates API successfully and enables the Next button as
expected. Just need to finish the installer in WIX and implement the DNS
update method for the application.
1) Updated JSON.net thinking it would fix a bug, but it was something
else.
2) FolderBrowser opens over the installer now, instead of center of
screen.
3) Errors look better with some newlines.
4) Removed duplicate documentation.
5) Overwrote RequestJSONAsync to centralize code/message checks.