Use a different encoding for individuals.

Unfortunately this also required rewriting lots of stuff,
including the local search.
Make batch_test executable.
Added exercise 1.

This classifies spam mail using kmeans and the tf-idf model.
The mail dataset was taken from:
http://csmining.org/index.php/spam-email-datasets-.html
Started report.
More report.
Merge pull request #1 from guilherme-pg/master

Exercises 1 and 3