REACH-92 Wrong positions of nodes after opening a file

Description of the bug is here: http://adsk-oss.myjetbrains.com/youtrack/issue/REACH-92

The solution suggested in this PR is to update nodes' positions right before saving a workspace. Flood sends `UpdateCoordinatesMessage` with current positions of nodes before sending `FileSaveMessage`, Dynamo processes this message and updates nodes in a specified workspace.

We cannot use corresponding `RecordableCommand` (`DragSelectionCommand`) because it's implemented to do all proper actions only in view.
Redundant else clause. Inside if clause you have 'return' statement, so you can skip else keyword and move code after 
'''
if (string.IsNullOrEmpty(guidStr))
        {
                return dynamoModel.HomeSpace;
        }
'''
outside of curly braces