Update License Copyright - Add custom propagation info to ReadMe (#6)

* add tracer init to readme

* added build and release features

* fix makefile typo

* can enable shared spans if desired

* add ability to provide custom propagation headers if needed. default to Span-ID, Trace-Id, Parent-ID

* fix lint issue

* fix copywrite in license and add re-org readme

* fix typo

LICENSE

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright [yyyy] [name of copyright owner]
+   Copyright 2019 Expedia, Inc.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

README.md

@@ -7,7 +7,8 @@ This is Haystack's client library for Python that implements [OpenTracing](https
 Further information can be found on [opentracing.io](https://opentracing.io/) 
 
 ## Using this library
-See examples in /examples directory. 
+See examples in /examples directory. See opentracing [usage](https://github.com/opentracing/opentracing-python/#usage) for additional information.
+
 
 First initialize the tracer at the application level by supplying a service name and recorder
 ```python
@@ -18,10 +19,6 @@ from haystack import HaystackTracer
 opentracing.tracer = HaystackTracer("a_service", HaystackAgentRecorder())
 ```
 
-**If there is a Scope, it will act as the parent to any newly started Span** unless the programmer passes 
-`ignore_active_span=True` at `start_span()/start_active_span()` time or specified parent context explicitly using 
-`childOf=parent_context`
-
 Starting a span can be done as a managed resource using `start_active_span()`
 ```python
 with opentracing.tracer.start_active_span("span-name") as scope:
@@ -35,7 +32,16 @@ do_stuff()
 span.finish()
 ```
 
-See opentracing [usage](https://github.com/opentracing/opentracing-python/#usage) for additional information.
+Note: **If there is a Scope, it will act as the parent to any newly started Span** unless the programmer passes 
+`ignore_active_span=True` at `start_span()/start_active_span()` time or specified parent context explicitly using 
+`childOf=parent_context`
+
+#### Custom propagation headers
+If necessary, default propagation headers can be replaced with custom ones by specifying custom propagator options. Register the new propagator with the tracer once configured. 
+```python
+prop_opts = PropagatorOpts("X-Trace-ID", "X-Span-ID", "X-Parent-Span", "X-baggage-")
+opentracing.tracer.register_propagator(opentracing.Format.HTTP_HEADERS, TextPropagator(prop_opts))
+```
 
 #### Logging
 All modules define their logger via `logging.getLogger(__name__)`