FIXES: #2527
* define custom docker image for travis-linux builds based on
package build image
* add macos builds
* add windows builds (currently allowed to fail)
* improve build and shell scripts as required for the CI envs
* add asio timer latency workaround
* omit several manual tests from TravisCI which cause memory exhaustion
- Add docker container tags for "latest_BRANCH"
- Prevent different branches from overwriting deb repo artifacts
- Manual approval always required before pushing to prod