Create safe query function

[obitech]

We need to make sure the connection and cursor is properly closed even if an exception is thrown.

Idea:

# ... other imports ...
from contextlib import closing

def query(db_name, sql):
    """Performs a database query and returns the result.

    It will uses contextlib to safely wrap a sqlite3 connection and
    a cursor to ensure the connection safely commits and closes (same
    as the cursor) in both happy and sad paths.

    Args:
        db_name (str): The name of the sqlite3 database to open.
        sql (str): The SQL query to perform.

    Returns:
        list: A list of tuples that gets returned by the performed query,
            as with calling ``cursor.fetchall()``. This will return an empty
            list in case nothing gets returned (such as for an UPDATE).
    """
    # Auto-closes
    with closing(sqlite3.connect(db_name)) as conn:
        # Auto-commits
        with conn:
            # Auto-closes
            with contextlib.closing(conn.cursor()) as cur:
                cur.execute(sql)
                return cur.fetchall()

You can then use wrap this in the try...except block:

try:
    # This will create a tuple that can be passed to the cursor
    query_tuple = "insert into Events values (?,?,?,?,?,?)", # .... 
    query(DB_NAME, query_tuple)
except sqlite3.IntegrityError as e:
    logging.error(e)

This needs to be unit-tested as well.