Use `defaults write` to create a plist file for Yosemite compatibility

[idpaterson]

make new property list file does not work in Yosemite unless the file already exists. This change initializes the plist file with a garbage value that is overwritten by make new property list file.

Unfortunately, there are more serious issues with UI automation in Yosemite that cripple my workflow, but this one was resolvable. Thanks @surrealroad for the suggested fix in issue #5!