[Users] New thorns for standard thorn list

I suggest to add the following thorns to our standard Einstein Toolkit thorn list:

Web 2.0 technologies for accessing and announcing Cactus simulation results:

ExternalLibraries/curl ExternalLibraries/flickcurl ExternalLibraries/libxml2 LSUThorns/Flickr LSUThorns/Twitter

Interesting run-time statistics:

AEIThorns/SystemStatistics

Useful external libraries:

ExternalLibraries/CGNS ExternalLibraries/HYPRE

Not all these libraries work / can be built on all HPC systems, although they all work on standard Linux systems with gcc or Intel compilers. The simulation factory has an mdb entry "disabled-thorns" that describes which thorns need to be disabled on what system. (These entries are probably not up to date in the Perl version of Simfactory.)

-erik