readme
Merge pull request #167 from ndawe/master

readme fixes
rootpy script: use find_files in sum() to avoid limit on number of cmd args
yield full path in find_files
minor edit
rootpy script: catch ROOTErrors if ROOT can't open the TFile
clean exit on KeyboardInterrupt
Merge pull request #168 from ndawe/master

More robust error handling in the rootpy script (and other minor fixes)