Gitignore fix

I removed the .suo file from the repository, since it contains only data about user specific setup. http://msdn.microsoft.com/en-us/library/vstudio/bb165909.aspx

I think it will be more familiar to most developers if the .gitignore file is in the root. It might be worth to use a "standard" .gitignore file like: https://github.com/github/gitignore/blob/master/VisualStudio.gitignore