jtimon is now using golang's dep so we no longer need to go "go get ..."

for dependent go packages in Dockerfile. The advantage is if in future
jtimon brings in new go package as dependent package we do not need to
modify Dockerfile.

Dockerfile

@@ -4,18 +4,13 @@
 FROM alpine:3.7
 RUN apk add --no-cache ethtool
 RUN apk add --no-cache --virtual build-dependencies git go musl-dev \
-  && go get github.com/golang/protobuf/proto \
-  && go get github.com/gorilla/mux \
-  && go get github.com/influxdata/influxdb/client/v2 \
-  && go get github.com/prometheus/client_golang/prometheus/promhttp \
-  && go get github.com/spf13/pflag \
-  && go get golang.org/x/net/context \
-  && go get google.golang.org/grpc \
-  && go get github.com/nileshsimaria/jtimon/telemetry \
-  && go get github.com/nileshsimaria/jtimon/authentication \
+  && mkdir -p /root/go/src/github.com/nileshsimaria \
+  && cd /root/go/src/github.com/nileshsimaria \
   && git clone https://github.com/nileshsimaria/jtimon.git \
   && cd jtimon && go build && strip jtimon && mv jtimon /usr/local/bin \
-  && cd .. && rm -rf jtimon && apk del build-dependencies
+  && cd / \
+  && rm -fr /root/go \
+  && apk del build-dependencies
 
 VOLUME /u
 WORKDIR /u