Remove introduction text on when reading from STDIN

[asdine]

Currently, whenever we are passing SQL queries to stdin we are also displaying the introduction header:

$ echo "SELECT 1 + 1" | genji
Opened an in-memory database.
Enter ".help" for usage hints.
{
  "1 + 1": 2
}

We want that text to be removed:

$ echo "SELECT 1 + 1" | genji
{
  "1 + 1": 2
}