Use exometer:re_register for counter registration, as an option or give us example?

[linearregression]

I use both config and progemmatically register new counter entey.
It will complains on counter exists.
Feuerlabs/exometer_core#70
per ulf:
"
you are unsure about whether the predef file gets loaded more than once, and you don't want to manually check before registering, you can use {re_register, {Name, Type, Options}}.

An obvious improvement would of course be that exometer recognizes that it's already registered the application at startup."