Need improvements around missing database files

[jmeaster30]

simpledns/src/simple_database.rs

Line 17 in dcd2e71

connection: Connection::open(database_file).unwrap(),

This unwraps the connection which can't be made if the db file doesn't exist so it panics

Two options for solving IMO:

1. Return a result from the SimpleDatabase constructor.
   • Error should indicate to the user that they need to run the init command to set up database file.
   • PRO: Easier
   • CON: Infectious error handling (not TERRIBLE because explicit is better but complicates code a bit)
2. Just initialize the database right there.
   • PRO: User doesn't have to run a separate command and we can probably remove the init command possibly
   • CON: Need consideration in implementation with multiple threads and what not