Aggregated pull request (CSV load from web, ranges fix, automatic tagging, R provider update)

This unifies and replaces all the existing pull requests:

 * Allow Read CSV to work over HTTP (and other non-seekable) streams (#227)
 * Handle unioning and intersecting with empty ranges (#229)
 * Automatically tag releases in build script (#228)

And some new work:

 * Update R provider reference to new version (which works without VS 2012)