added DeploymentItemExAttribute, much like DeploymentItem, but supports long file paths

Notice there are two "// TODO:" items.

1. The ability to output warnings to the test results log file.

Is this possible?

2. The ability to get the value of the RelativePathRoot property setting in the current .testsettings file

See this msdn article for more information:
http://msdn.microsoft.com/en-us/library/ms182475%28v=vs.100%29.aspx
"Relative paths are relative to the RelativePathRoot setting found in the .testrunconfig file."

I could not personally find this specific setting, so I'm not sure if this is just a documentation error.  I've also read that it is set to the solution directory by default, so that is what I am trying to use for now.

Once this new attribute looks good, I can go ahead and try to add unit\integration tests for it.

What do you think?

Thank you.