ensure that job_id is Mango::BSON object

This patch fixed bug with show info about job in minion command

```bash
./script/app minion job 538e169a5fbd2d0ed9bc0000
Can't use string ("538e169a5fbd2d0ed9bc0000") as a HASH ref while "strict refs" in use at /home/and/perl5/perlbrew/perls/perl-5.20.0/lib/site_perl/5.20.0/Mango/BSON.pm line 87.
```