Add get_tracer and get_Current_span to __init__

Author: Tanner Bruce

django_opentracing/__init__.py

@@ -1,2 +1,2 @@
 from .middleware import OpenTracingMiddleware
-from .tracer import DjangoTracer
+from .tracer import DjangoTracer, get_current_span, get_tracer

django_opentracing/tracer.py

@@ -9,7 +9,7 @@ def get_tracer():
 def get_current_span(request):
     # this lets django rest framework work seamlessly since they wrap the request
     if hasattr(request, '_request'):
-        request = _request
+        request = request._request
     return django_tracer.get_span(request)