Install "time" so that we can profile things

tools/dockerfile/grpc_sanity/Dockerfile

@@ -73,6 +73,10 @@ RUN pip install simplejson mako
 RUN curl https://get.docker.com/ | sh
 RUN apt-get remove --purge -y docker-engine
 
+##################
+# Build profiling
+RUN apt-get install -y time
+
 RUN mkdir /var/local/jenkins
 
 # Define the default command.

tools/dockerfile/grpc_tests_multilang_x64/Dockerfile

@@ -153,6 +153,10 @@ RUN apt-get update && apt-get install -y \
 # Zookeeper dependencies
 RUN apt-get install -y libzookeeper-mt-dev
 
+##################
+# Build profiling
+RUN apt-get install -y time
+
 RUN mkdir /var/local/jenkins
 
 # Define the default command.

tools/dockerfile/grpc_tests_multilang_x86/Dockerfile

@@ -152,6 +152,9 @@ RUN apt-get update && apt-get install -y \
 # Zookeeper dependencies
 RUN apt-get install -y libzookeeper-mt-dev
 
+##################
+# Build profiling
+RUN apt-get install -y time
 
 RUN mkdir /var/local/jenkins