change config parsing order
change config parsing order

Given FLOW_CONFIG_PATH=foo:bar being used to execute `flow subcommand`,
the previous method would search through these files in order:

foo/subcommand.yaml, foo/flow.yaml, bar/subcommand.yaml, bar/flow.yaml

This created a situation where it was hard to override, e.g., logging
config for a particular command in both production and development, so
the new resolution order is:

foo/subcommand.yaml, bar/subcommand.yaml, foo/flow.yaml, bar/flow.yaml

genome/flow-core,genome/flow-core,genome/flow-core