Updated installation instructions taking into account config.json
Changed node.js install from optional to if not already installed
updating ADL Node xAPI package name xapiwrapper-node -> adl-xapiwrapper
Merge pull request #101 from imartinezortiz/adl-xapiwrapper

updating ADL Node xAPI package name xapiwrapper-node -> adl-xapiwrapper
Merge remote-tracking branch 'origin/master' into v0.4.8_candidate