Refactor `SummerBuilder` to make it possible to use `Counters` on `SummerBuilder` creation

[ttim]

Currently the way to customize Summer instances is not perfect - we have an old 'legacy' way based on a lot of different options and 'new' way with setting SummerBuilder directly. At the same time with new way it's impossible to fully utilize Counters because jobId is needed to create them. Also new way is quite verbose.

This PR adds a way to use Counters in SummerBuilder and couple of SummerBuilders: Null, sync and async.

[ttim]

There is an issue for that: https://github.com/twitter/summingbird/issues/711

[codecov-io]

Codecov Report

Merging #738 into develop will decrease coverage by 0.13%. The diff coverage is 39.28%.

@@             Coverage Diff             @@
##           develop     #738      +/-   ##
===========================================
- Coverage    71.99%   71.86%   -0.14%     
===========================================
  Files          152      153       +1     
  Lines         3721     3735      +14     
  Branches       208      202       -6     
===========================================
+ Hits          2679     2684       +5     
- Misses        1042     1051       +9

Impacted Files	Coverage Δ
...om/twitter/summingbird/online/option/AllOpts.scala	62.5% <0%> (-20.84%)	:arrow_down:
...om/twitter/summingbird/online/option/Summers.scala	32.35% <32.35%> (ø)
...la/com/twitter/summingbird/storm/BuildSummer.scala	50% <55%> (+6.52%)	:arrow_up:
.../twitter/summingbird/memory/ConcurrentMemory.scala	97.14% <0%> (+1.42%)	:arrow_up:
.../main/scala/com/twitter/summingbird/Producer.scala	77.27% <0%> (+1.51%)	:arrow_up:

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[ttim]

@johnynek I know here is quite a lot of code without test coverage, if you think it worth it to add tests on that - I can do this. But personally I think it's ok to leave this kind of code without tests.

[ttim]

@johnynek @pankajroark can you look again did I point all your comments? Thanks!

[johnynek]

👍