Changes introduced in 982af05 caused the RDP configuration file to be written
with all settings on one line instead of one setting per line. The Microsoft
Remote Desktop client for OS X rejects these configuration files as being
malformed. This patch restores the configuration to one line per setting and
adds tests to guard against regression.
This commit basically grepped the code base for all uses of Dir.mktmpdir
and Tempfile.new/open and ensures the value is unique within the
code base and also prefixed with `vagrant-`.
Previously, most invocations of these commands simply used "vagrant",
thus making them indistinguishable when trying to identify leaks.