prepare automatic security scanning (#122)

* add todo for docker wait
* add makefile target to scan containers with trivy
* pin version of trivy in travis file
* add trivy cache to persistent storage of travis (commented since not part of ci for the moment)
* reorg travis file + remove goss as it is not used
* add a fixed version for the base image
* add file with tags to gitignore
* introduce tag-all target
* remove after_failure step
* add ignore file for trivy
* store the tag for the builder as well
* remove tag_file after completing scans
* replace manual build and publish commands with generated ones
* update kdav builder to resolve CVE-2019-3855
* ignore CVE-2019-3855 which is thrown in kdav build container
* exclude the build-webapp-demo from build-all

base/Dockerfile

@@ -3,6 +3,8 @@ FROM debian:stretch
 LABEL maintainer=az@zok.xyz \
       version="2.0"
 
+ENV BASE_VERSION=1.0
+
 RUN mkdir -p /kopano/repo /kopano/data /kopano/helper /kopano/path
 WORKDIR /kopano/repo
 
@@ -46,6 +48,6 @@ ARG RELEASE_KEY_DOWNLOAD=0
 # get common utilities
 COPY create-kopano-repo.sh /kopano/helper/
 COPY kcconf.py /kopano/
-RUN date +%s > /kopano/buildversion
+RUN echo $BASE_VERSION > /kopano/buildversion
 
 SHELL [ "/bin/bash", "-c"]