Added basic TelemetryAgent configuration tests
Added TransformerTest and started on HttpServlet handler tests
Extracted duplicate handler behaviour to SubTypeInstrumentationHandler
Changed ids from long to BigInteger.

This is to avoid issues between ids passed from ruby where they are
unsigned 64 bit ints to java where they are signed longs (also 64 bits).
Added guard for cases where trace has a null root.

This happens when we receive requests from other systems.
Added rule to identify unclosed spans in tests, improved test coverage
Added log sink configuration and an asynchronous log writer
Removed unused method
Added sampling on/off configuration for Span class.

The default sampling is on which means behaviour is unchanged but it is
now possible to disable tracing unless going through the attachSpan
method.  i.e  if an incoming request has trace and span ids we will
record it otherwise we won't.
Added configuration to allow turning tracing on and off.

Incoming requests with traceId and spanId headers will still be
recorded.
Metrics Handler working in Example Service, Unit tests cleaned up slightly
Pulled out telemetry-instrumentation and telemetry-test-framework modules tested MetricsHandler
Added start of ApacheHttpClient unit tests
Removing debug trace
Define guava version at the top
Added Counter annotation instrumentation for Metrics.
Changed timer instrumentation from span to annotations.
Removing dependency on telemetry-service-sink

This is to avoid pulling all of its dependencies into the agent jar
file.
Adding an resource which uses an executor to run background tasks.
Instrumenting Executors created via dropwizard Environment.managed*Executor

This get swapped for the InstrumentedThreadPoolExecutor or
InstrumentedScheduledThreadPoolExecutor which in turn decorate or wrap
tasks in InstrumentedRunnableFuture or
InstrumentedRunnableScheduledFuture.

This instrumentation adds annotations for when a task is
scheduled/submitted, when it starts and when it ends.
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