0.3.0

• Added sample code for constructing and injecting OpsLogger instances with Dagger (Issue #11)
• Support multi-enum OpsLogger usage (Issue #6) : calling build() multiple times with different type tokens will return the same instance if the actual logging configuration hasn't changed.
• Add the concept of global and local diagnostic contexts. A global DiagnosticContextSupplier is registered with OpsLoggerFactory and will usually track context information via ThreadLocal variables or a similar mechanism. Local DiagnosticContextSupplier instances are passed directly into the OpsLogger instance by the logging class. Using the global supplier is usually more convenient, but local suppliers work in situations where the global ones might not. In particular, ForkJoinPool workers and Java 8 parallel stream processing workers run on many threads and can't rely on ThreadLocal variables.