Add example for excel to json with mapper from file and add docker support

examples/excel2json/Dockerfile

@@ -0,0 +1,14 @@
+FROM cubetiq/calpine-node:latest
+LABEL maintainer="sombochea@cubetiqs.com"
+
+ENV INPUT_FILE './data/people.xlsx'
+ENV OUTPUT_PATH './data/outputs'
+ENV MAPPER_FILE './data/mapper.json'
+
+WORKDIR /usr/src/app
+
+COPY . /usr/src/app
+
+RUN yarn
+
+CMD [ "node" , "index.js"]