Using sqlite db in test_components

The dates are set in EmComponent::create() for date_create and in EmComponent::save() for date_update
The values are sets to datetime.datetime.utcnow() so we now that EVERY date in the db are in UTC, no matter django, database or even server configurations.
We will have to take care to convert dates from database to django timezone in dates fieldtypes.

Added a classmethod EmComponent::newUid() that determines the caller's class and return a newly registrated UID

Put every uid columns and associated FK in INTEGER instead of VARCHAR(50)

Adding a column is implemented for mysql, postgresql and sqlite.
Droping and altering a column is only implemented for mysql and postgresql for the moment.

Quick&dirty tests has been done  for sqlite and mysql only.

Now SQLSetup in able (via initDb) to initialize the database.
WARNING : initDb start by droping all tables in database before creating the new ones

Removed logging test in EditorialModel/lib/component.py
Added comment in Database/sqlwrapper.py