Changed base image to maven to give FOSSA access to maven

During scans, FOSSA seems to use maven commands, so we want these to be
generally available. The 'maven' image already contains curl, wget, and bash; so
we can also skip adding those.

Dockerfile

-FROM alpine
+FROM maven
 
-RUN apk add bash curl wget
 RUN curl https://raw.githubusercontent.com/fossas/fossa-cli/master/install.sh | bash