Twitter access keys, first problem's solution
Basic implementation to solve the problem 2: just single word

* The dictionaries entries composed of more than one word aren't
been used.
Code to generate almost the same output of the problem 2

* As probably I must pass over a tweet content twice, I tried
to avoid the repetition of line splitting and word normalization.
Computation of the new words' score is finished
Solution for the problem 4
wip: Started printing the tweets' country for problem 5
Final solution for problem 5

* Only the field place.fullname was used to locate the tweet.
* First the State's abbreviation is checked; if it was not found,
the State's name is checked.
Solution for the problem 6
Solutions for the assignment 2's problems
Solution of assignment3-problem1 using class

* The solution seems to be right, but it was not
accepted by the Coursera's system.
Modifications to satisfy the submission system
Map-Reduce join