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 branch 'master' into development
Merge branch 'development' into vle