Support specifying project ids for migration

This commit will support the specification of projects to migrate by one or more given project id identifiers, and also by a csv file list.

So long as the project.repository_storage is the same as the specified source --current-file-server=source-fqdn then only projects given by the command line argument --project=PROJECT_ID,... will be replicated to the given destination, --target-file-server=destination-fqdn.

There are also a large amount of changes toward the goal of getting all scripts/storage_rebalance.rb passing rubocop checks (#26 (closed)).