Upgrade to metrics-core 3.0.1
Merge pull request #8 from scullxbones/metrics-3-for-actors-and-futures

Add support for metrics on actors
Merge pull request #10 from bretthoerner/3.0.1

Upgrade to metrics-core 3.0.1
Remove $'s from metrics names (fixes #11).
Even better removal of $'s from metrics names (fixes #11).
Removed converters from core metric to scala wrapper and back.
Formatting issues.
Prepared for 3.0.1.
add inc/dec on Counter
Merge pull request #14 from alexy/master

add inc/dec on Counter