Fix the --ivy-report option and add integration test

I inadvertently broke this back at https://rbcommons.com/s/twitter/r/941/ by  removing the override from pants.ini
I went back and audited other bootstrap-tools references and made them absolute address specs and made sure they were surrounded in '[]'

Testing Done:
CI passed, invoking with --ivy-report manually from the command line no long throws an exception and creates a report.

Bugs closed: 545

Reviewed at https://rbcommons.com/s/twitter/r/976/