[SonataImportBundle] Use ImporterInterface in import admin #50

Job	Run time
After Split Testing of application	55s
After Split Testing of aws-tool-kit	46s
After Split Testing of console	54s
After Split Testing of core	45s
After Split Testing of cron-job	48s
After Split Testing of doctrine-extra	46s
After Split Testing of entity-migrator	48s
After Split Testing of fixer	43s
After Split Testing of framework-extra-bundle	49s
After Split Testing of log	46s
After Split Testing of mailer	45s
After Split Testing of messenger	56s
After Split Testing of open-api	46s
After Split Testing of process	53s
After Split Testing of profiling	45s
After Split Testing of security	45s
After Split Testing of sonata-import-bundle	1m 3s
After Split Testing of sonata-integration-bundle	49s
After Split Testing of sonata-extra-bundle	49s
After Split Testing of tester	53s
After Split Testing of tester-bundle	51s
After Split Testing of user-bundle	45s
After Split Testing of validator	55s
After Split Testing of workflow	45s
	19m 40s

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