newsbeuter 2.8 for mavericks

I made newsbeuter 2.8 compile under Mavericks 10.9.1 + `Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)` from Xcode Xcode 5.0.2 Build version 5A3005.

The fix consists in removing the use of the `tr1` namespace by altering include statements and namespace syntax. Apparently, this is something that won't happen in upstream until their C++11 branch is eventually merged. In the meantime, this updated formula makes newsbeuter happen on Mavericks again.

Hope that helps.

PS: I didn't use `inreplace` because it complains when no substitution is made in a file (which happens by the nature of my globbing search).