Fix saltstack bootstrap renaming desired to be installed package from
swig -> swig30 since former package doesn't exist

PR: 226830
Submitted by: garga
Approved by: maintainer timeout (> 2 weeks)
Obtained from: https://github.com/saltstack/salt-bootstrap/issues/1192
MFH: 2018Q2
Sponsored by: Rubicon communications, LLC (Netgate)