Fix stack overflow on display error

[Aceeri]

If you did println!("{}", err); it would stack overflow because the Display impl recursively called Display::fmt on itself here

[ufoscout]

This issue is still present in the master branch and it causes a stack overflow if the credentials to connect to Jira are not valid.

Here a simple way to fix it:

change from:

writeln!(f, "Could not connect to Jira: {}!", self),

to:

writeln!(f, "Could not connect to Jira: {:?}!", self),