Remove vendor proto files and use opencensus-proto instead. (#596)

* Remove vendor proto files and use opencensus-proto instead.

* Update requires.

* Remove gen files from coveragerc

* Update version.

Author: songy23

.coveragerc

@@ -6,7 +6,6 @@ omit =
     contrib/*/tests/*
     # Auto generated files
     contrib/opencensus-ext-jaeger/opencensus/ext/jaeger/trace_exporter/gen/*
-    contrib/opencensus-ext-ocagent/opencensus/ext/ocagent/trace_exporter/gen/*
     # Side-effect introduced by namespace packages
     opencensus/__init__.py
     opencensus/common/__init__.py
@@ -29,4 +28,3 @@ omit =
     opencensus/common/__init__.py
     # Auto generated files
     contrib/opencensus-ext-jaeger/opencensus/ext/jaeger/trace_exporter/gen/*
-    contrib/opencensus-ext-ocagent/opencensus/ext/ocagent/trace_exporter/gen/*

contrib/opencensus-ext-ocagent/opencensus/ext/ocagent/trace_exporter/__init__.py

@@ -22,12 +22,9 @@
 from opencensus.common.transports import sync
 from opencensus.common.version import __version__
 from opencensus.ext.ocagent.trace_exporter import utils
-from opencensus.ext.ocagent.trace_exporter.gen.opencensus.agent.common.v1 \
-    import common_pb2
-from opencensus.ext.ocagent.trace_exporter.gen.opencensus.agent.trace.v1 \
-    import trace_service_pb2
-from opencensus.ext.ocagent.trace_exporter.gen.opencensus.agent.trace.v1 \
-    import trace_service_pb2_grpc
+from opencensus.proto.agent.common.v1 import common_pb2
+from opencensus.proto.agent.trace.v1 import trace_service_pb2
+from opencensus.proto.agent.trace.v1 import trace_service_pb2_grpc
 from opencensus.trace import base_exporter
 
 # Default agent endpoint