com_github_rapidjson -> com_github_tencent_rapidjson (#266)

* Matches URL.
* Matches what Envoy calls it.

Author: g-easy

WORKSPACE

@@ -122,7 +122,7 @@ cc_library(
 
 # Rapidjson library - used by zipkin exporter.
 http_archive(
-    name = "com_github_rapidjson",
+    name = "com_github_tencent_rapidjson",
     build_file_content =
         """
 cc_library(

opencensus/exporters/trace/zipkin/BUILD

@@ -33,7 +33,7 @@ cc_library(
     deps = [
         "//opencensus/trace",
         "@com_github_curl//:curl",
-        "@com_github_rapidjson//:rapidjson",
+        "@com_github_tencent_rapidjson//:rapidjson",
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",