MigrationImportSuite: use ZeroTime() and clarify time import
MigrationImportSuite: use ZeroTime() and clarify time import

reedobrien/juju,bz2/juju,dimitern/juju,frankban/juju,anastasiamac/juju,perrito666/juju,alesstimec/juju,gabriel-samfira/juju,AdamIsrael/juju,reedobrien/juju,perrito666/juju,reedobrien/juju,ericsnowcurrently/juju,mjs/juju,frankban/juju,axw/juju,AdamIsrael/juju,macgreagoir/juju,waigani/juju,axw/juju,macgreagoir/juju,mjs/juju,alesstimec/juju,axw/juju,waigani/juju,mjs/juju,marcmolla/juju,ericsnowcurrently/juju,bz2/juju,ericsnowcurrently/juju,mjs/juju,bz2/juju,macgreagoir/juju,frankban/juju,mjs/juju,gabriel-samfira/juju,dimitern/juju,bac/juju,marcmolla/juju,howbazaar/juju,waigani/juju,frankban/juju,bac/juju,mikemccracken/juju,gabriel-samfira/juju,mikemccracken/juju,anastasiamac/juju,axw/juju,AdamIsrael/juju,howbazaar/juju,howbazaar/juju,mikemccracken/juju,bz2/juju,macgreagoir/juju,axw/juju,reedobrien/juju,perrito666/juju,macgreagoir/juju,bz2/juju,anastasiamac/juju,alesstimec/juju,ericsnowcurrently/juju,anastasiamac/juju,marcmolla/juju,mjs/juju,perrito666/juju,mikemccracken/juju,dimitern/juju,anastasiamac/juju,mikemccracken/juju,frankban/juju,gabriel-samfira/juju,bac/juju,gabriel-samfira/juju,reedobrien/juju,alesstimec/juju,waigani/juju,ericsnowcurrently/juju,alesstimec/juju,bac/juju,marcmolla/juju,howbazaar/juju,perrito666/juju,marcmolla/juju,howbazaar/juju,dimitern/juju,AdamIsrael/juju,bac/juju,mjs/juju,dimitern/juju