Updated README to include installation instructions for XNAT modules.
Updated README to include installation instructions for XNAT modules.

evast/XNATImageViewer,evast/XNATImageViewer,evast/XNATImageViewer,rherrick/XNATImageViewer,rherrick/XNATImageViewer,evast/XNATImageViewer,evast/XNATImageViewer,rherrick/XNATImageViewer,hodgem/XNATImageViewer,rherrick/XNATImageViewer,hodgem/XNATImageViewer,hodgem/XNATImageViewer,hodgem/XNATImageViewer,rherrick/XNATImageViewer,hodgem/XNATImageViewer