Create or Alter table

In case the table does not exist, it will create the table.
In case it already exist, it will add the new columns to the table.

=> todo: We will need to check if we have a 'NOT NULL' condition in the
new columns.
   In this case, we need to ensure that 'DEFAULT' is given.

* addColumns(string tableName, object newColumns)

* createOrAlterTable(string tableName, object iColumns)