Merge pull request #15 from anacmendes/master

Alterações ao dia 1
Guia - dia2

Guia - dia2
Merge pull request #17 from MarianaAlmeida/master

Guia - dia2
TXT Introduction to mapreduce
MIN Add Big Data labs to main doc
UPD Fill in details
ENH Start word count
COD Copy & paste in the code for Big Data I
Merge pull request #18 from luispedro/master

Big Data Day I
MIN Fix copy & paste
Removed .log files
Small change in the classification part. Changed the sequences chapter to conform with the previous chapter. Namely, introduced reference to the assignment of the lecture. Changed a bit the structure to make the chapter more understable (IMHO) and corrected a few issues