Extract path configurations for Revit System Tests
RevitTestConfiguration
Set default values to RevitTestConfiguration

- When some of the properties are not set, SetDefaultValues() method
will set the default values to all the properties which are null or
empty.
Rename SetDefaultValues to SetDefaultValuesToUninitializedProperties
Merge pull request #3272 from Conceptual-Design/DynamoRevit2014

Extract path configurations for Revit System Tests
Merge branch 'DynamoRevit2014' of https://github.com/DynamoDS/Dynamo into RevitTestConfig
xml file is renamed to RevitTestConfiguration.xml