Bump md-addins, fixes breakage caused by Xcode 4.6.2

Changes XcodeRevision to float.

This is needed due to a change in the CFBundleVersion in Xcode.app/Contents/Info.plist 

We are expecting the string to be parseable into ints in MonoDevelop.MacDev/MonoDevelop.MacDev/AppleSdkSettings.cs:183

XcodeRevision = int.Parse (value.Value);

4.6.2 
<key>CFBundleVersion</key>
	<string>2067.2</string>

4.6.0
<key>CFBundleVersion</key>
	<string>2066</string>