Expect 'sampled' header to be unicode already

This was a bug. I have no idea why I did it that way. The string is
always unicode in Py2.7 and Py3.4+ from what I can tell. The
.decode(utf8) before my changes was probably an unnecessary no-op.

This should fix #278 by properly parsing the header.

baseplate/integration/pyramid/__init__.py

@@ -218,7 +218,7 @@ def _start_server_span(self, request, name, trace_info=None):
 
     def _get_trace_info(self, headers):
         extracted_values = TraceInfo.extract_upstream_header_values(TRACE_HEADER_NAMES, headers)
-        sampled = bool(extracted_values.get("sampled") == b"1")
+        sampled = bool(extracted_values.get("sampled") == "1")
         flags = extracted_values.get("flags", None)
         return TraceInfo.from_upstream(
             int(extracted_values["trace_id"]),

tests/integration/pyramid_tests.py

@@ -160,7 +160,7 @@ def test_trace_headers(self):
             "X-Trace": "1234",
             "X-Parent": "2345",
             "X-Span": "3456",
-            "X-Sampled": b"1",
+            "X-Sampled": "1",
             "X-Flags": "1",
         })
 
@@ -185,7 +185,7 @@ def test_b3_trace_headers(self):
             "X-B3-TraceId": "1234",
             "X-B3-ParentSpanId": "2345",
             "X-B3-SpanId": "3456",
-            "X-B3-Sampled": b"1",
+            "X-B3-Sampled": "1",
             "X-B3-Flags": "1",
         })