Added Dockerfile for alpine linux by @andresilva, closes #3565 (#8587)

docker/alpine/Dockerfile

@@ -0,0 +1,29 @@
+FROM alpine:3.7
+
+WORKDIR /build
+
+# install tools and dependencies
+RUN apk add --no-cache gcc musl-dev openssl-dev pkgconfig g++ make curl \
+					   eudev-dev rust cargo git file binutils libusb-dev \
+					   linux-headers
+
+# show backtraces
+ENV RUST_BACKTRACE 1
+
+# show tools
+RUN rustc -vV && \
+cargo -V && \
+gcc -v &&\
+g++ -v
+
+# build parity
+ADD . /build/parity
+RUN cd parity && \
+	cargo build --release --verbose && \
+	ls /build/parity/target/release/parity && \
+	strip /build/parity/target/release/parity
+
+RUN file /build/parity/target/release/parity
+
+EXPOSE 8080 8545 8180
+ENTRYPOINT ["/build/parity/target/release/parity"]