Merge pull request #1 from umbraco/master

Update from Umbraco master
Updating WebMatrix installation instructions

WebMatrix 3 is now the default version of the software available from
Microsoft. Umbraco's installation instructions, however, were written
for the original WebMatrix. I have updated the written instructions in
order to follow WebMatrix 3's screen prompts and also updated a few of
the screen shots.
Correcting image file names from previous commit

In my commit from about 45 minutes ago, I messed up the image filenames.
I've corrected them here.
Continued image file name changes

Same as last commit from me.
Merge pull request #124 from brentmiller/master

 Updating WebMatrix installation instructions