change the db schema and renamed the 'companies' to 'mediators'
changed the databse schema and added a table 'enterprises' that will hold the information of irstrat's clients. so far it will hold the information for Terra and Azteca Bas.
changed the database schema in order to add a FK for 'stock_owner' in the table 'infosel_stock_actions' and removed the unnecessary table related to the data sources

important things to take into account:
. the table 'infosel_stock_actions' holds the actions for the 'infosel' data source and therefore it is no longer needed.
changed the database schema in order to populate the enterprises table and enforce an unique behavior in the 'enterprise_ticker' column