Integration of SqlAlchemy classes in mlstats
ci: Update .travis.yml for continuous integration
dbn: Remove unused methods
Remove old database code
db: Move new database implementation in the old namespace

Last step to replace the old database implementation with
SqlAlchemy
db: Implements back get_compressed_files

It was accidentally removed (not implemented) in the
port to SQLAlchemy.
db: Force convert to unicode for MySQL dialect
Simplify logging information
Remove admin parameters to the create database

Since SqlAlchemy, we will rely on the user to create the
database, though we will create the tables if they don't
exists. Therefore, this option does not makes sense anymore.
tests: Update tests according to latest changes in analyzer

We now returns a datetime instead of a ISO string, therefore,
the test should reflect that comparison
setup: Update meta data
database: add mailing_list_url to primary key in messages table

This change on the database schema allows to store messages
that were sent to different mailing lists.

Applied this change according to commit ad6e5a48 done in the
old database code base.
db: Increase the length for column subject. Fixes #22

Some emails might have long subjects, as some users might write the
whole message there (by ignorance or mistake).  It is a rare case(TM),
and likely 1024 should be more than enough (so far the only case
reported was 322 chars long).