Separate Producer and Mindreader head block number and drift

[jubeless]

Currently the mindreader and the producer, both register a head block number & drift with the name "manager". This has as effect that dfuse-eosio cannot distinguish between both application for the metric value head_block_number & head_block_time_drift. We need to configure the name of the Head block number and drift metric on runtime.

while running dfuse-eosio locally, open your browser @ localhost:9102. Currently you should see

...
head_block_number{app="manager"} 170
...

the goal would be to see

...
head_block_number{app="producer"} 170
head_block_number{app="mindreader"} 172
...

PR: https://github.com/dfuse-io/manageos/pull/1