Fix a typo in INSTALL.md

Pretty sure what's intended here is http://en.wiktionary.org/wiki/voil%C3%A0, not the musical instrument.
Merge pull request #610 from Atheros1/master

Chinese translation
Merge pull request #608 from Michagogo/patch-1

Fix a typo in INSTALL.md
Fix #611; also swap print statements out for loggers