Replace Dockerfile Alpine linux with Ubuntu (prebid#885)

* Ubuntu dockerfile works, includes backups and out file

* Ubuntu Dockerfile creates image successfully and prebid-server was tested with a sample request. Seems to work fine

* Ubuntu 18.04 now builds, validates.sh, and curls sample request successfully

* Removed sed command

Dockerfile

@@ -1,20 +1,24 @@
-FROM alpine:3.8 AS build
+FROM ubuntu:18.04 AS build
 WORKDIR /go/src/github.com/prebid/prebid-server/
-RUN apk add -U --no-cache go git dep musl-dev
+RUN apt-get update && \
+    apt-get -y upgrade && \
+    apt-get install -y git golang go-dep && \
+    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 ENV GOPATH /go
 ENV CGO_ENABLED 0
 COPY ./ ./
-RUN dep ensure
-RUN go build .
+RUN dep ensure && \
+    go build .
 
-
-FROM alpine:3.8 AS release
-MAINTAINER Hans Hjort <[email protected]>
+FROM ubuntu:18.04 AS release
+LABEL maintainer="[email protected]" 
 WORKDIR /usr/local/bin/
 COPY --from=build /go/src/github.com/prebid/prebid-server/prebid-server .
 COPY static static/
 COPY stored_requests/data stored_requests/data
-RUN apk add -U --no-cache ca-certificates mtr
+RUN apt-get update && \
+    apt-get install -y ca-certificates mtr && \
+    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 EXPOSE 8000
 EXPOSE 8080
 ENTRYPOINT ["/usr/local/bin/prebid-server"]