* [msbuild] Added a PropertyListEditor task which works like PlistBuddy
This is a convenience Task for customers and isn't currently used
by the core MSBuild targets.
* [msbuild] The PropertyListEditor task does not need a SessionId property
* [msbuild] Added support for non-container root plist elements
* [msbuild] Catch & log exceptions loading plist document
Jeffrey Stedfast