+ kamon-examples: updated play example to the latest version
= kamon-examples: updated play example with the TraceName Action
= kamon-examples: fixes typo in TraceLocalFilter
= kamon-play-example: explain how run the example
= kamon-play-example: fixed typo
= core: Inline variant of withTraceContext using macros.
Merge remote-tracking branch 'crypticmind/master'
! all: refactor the core metric recording instruments and accomodate UserMetrics

This PR is including several changes to the kamon-core, most notably:
  - Formalize the interface for Histograms, Counters and MinMaxCounters. Making sure
    that the interfaces are as clean as possible.
  - Move away from the all Vector[Measurement] based Histogram snapshot to a new approach
    in which we use a single long to store both the index in the counts array and the
    frequency on that bucket. The leftmost 2 bytes of each long are used for storing the
    counts array index and the remaining 6 bytes are used for the actual count, and
    everything is put into a simple long array. This way only the buckets that actually
    have values will be included in the snapshot with the smallest possible memory
    footprint.
  - Introduce Gauges.
  - Reorganize the instrumentation for Akka and Scala and rewrite most of the tests
    of this components to avoid going through the subscription protocol to test.
  - Introduce trace tests and fixes on various tests.
  - Necessary changes on new relic, datadog and statsd modules to compile with the new
    codebase.

Pending:
  - Finish the upgrade of the new relic to the current model.
  - Introduce proper limit checks for histograms to ensure that we never pass the 2/6 bytes
    limits.
  - More testing, more testing, more testing.
  - Create the KamonStandalone module.
Merge branch 'wip/metrics-collection-refactor'

Conflicts:
	kamon-datadog/src/test/scala/kamon/datadog/DatadogMetricSenderSpec.scala
= build: ensure that the java code is also targeted to Java 1.6
= all: upgrade to Scala 2.10.4
+ core: introduce the new kamon.metrics.default-collection-context-buffer-size setting
= core: ensure that no automatic metric flushes occur during certain tests
+ play: introducing LoggerLikeInstrumentation in order to copy the properties of TraceLocalStorage to MDC
= play: comment test because not run in travis
= play: fixes LoggerLikeInstrumentationSpec
= build: ensure that no dependency to kamon-macros is exposed in the generated pom.xml
+ core: create the new KamonStandalone helper, closes #47
+ core: log a configurable error message when the application was started with the AspectJ Weaver, closes #48
= build: avoid unnecessary compile dependency on kamon-testkit from kamon-spray