JMH Perf Tests

1) Migrate all previous tests into `rx.archive` until we have matured with JMH
2) JMH config in gradle
3) Start of benchmarking with JMH for `baseline`, `map` and `serialize`

**To Run**

Inside ./rxjava-core/ invoke `../gradlew benchmarks`

Or from base invoke `./gradlew benchmarks` and it will scan each sub-module for benchmarks and then only find them in rxjava-core.

**Output**

```
Result : 72.204 ±(99.9%) 7.524 ns/op
  Statistics: (min, avg, max) = (69.221, 72.204, 74.048), stdev = 1.954
  Confidence interval (99.9%): [64.680, 79.729]


Benchmark                                                          (size)   Mode   Samples         Mean   Mean error    Units
r.jmh.Baseline.forLoopInvokingFunction                               1024   avgt         5     3230.689      486.080    ns/op
r.jmh.Baseline.forLoopInvokingFunction                            1048576   avgt         5  3394679.521   148858.373    ns/op
r.operators.OperatorMapPerf.mapIdentityFunction                         1   avgt         5       91.338        8.504    ns/op
r.operators.OperatorMapPerf.mapIdentityFunction                      1024   avgt         5     5626.727     1209.108    ns/op
r.operators.OperatorMapPerf.mapIdentityFunction                   1048576   avgt         5  6268747.085   258008.983    ns/op
r.operators.OperatorSerializePerf.noSerializationSingleThreaded      1024   avgt         5       42.198        0.791    ns/op
r.operators.OperatorSerializePerf.noSerializationSingleThreaded   1048576   avgt         5       45.935        0.911    ns/op
r.operators.OperatorSerializePerf.serializedSingleStream             1024   avgt         5       69.410       10.499    ns/op
r.operators.OperatorSerializePerf.serializedSingleStream          1048576   avgt         5       72.305       11.450    ns/op
r.operators.OperatorSerializePerf.synchronizedSingleStream           1024   avgt         5       72.238        7.233    ns/op
r.operators.OperatorSerializePerf.synchronizedSingleStream        1048576   avgt         5       72.204        7.524    ns/op


```