Suppress "Entry added" message if using default journal

[micahellison]

This PR fixes #1543 by suppressing output if you successfully add a new entry to your default journal.

If you're working on any other journal, it will still show the message. I hope this is a good compromise for jrnl's default behavior, though I think it's also worth revisiting later to see if we're best saved by a "quiet" or "verbose" mode.

Example of this behavior:

>jrnl this is a new entry to my default journal
>jrnl testing this is a new entry to my testing journal
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃  Entry added to testing journal  ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
>jrnl testign I wanted this to be a new entry in my testing journal but I misspelled the journal name
>

Feedback welcome!

Checklist

• I have read the contributing doc.
• I have included a link to the relevant issue number.
• I have checked to ensure there aren't other open pull requests
  for the same issue.
• I have written new tests for these changes, as needed.

[wren]

🦅