created HadoopTraffic module
Wrote introduction to Data set chapter
Added Chapter expaining how to use input from multiple files and run two part jobs
Added section explaining how to deal with WMR's emission limitations
Edits and added challenges
Merge branch 'jl-dev' into develop

Added AdvancedHadoop module
Merge branch 'develop' of https://github.com/libbyshoop/csinparallel into develop
created HadoopLastFM module