Fixed broken links and replaced 1 screen shot

Fixed a few inline and 1 external link in both topics, and replaced 1 screen shot. Changes: 

ITPro/Linux/CommonTasks/LinuxVHDCommonTask.md
ITPro/Linux/HowTo/howto-prepare-linux-distribution.md

New screen shot:
ITPro/Linux/Media/Storagenewaccount.png