[WIP] Add configuration through variables + tests

[olblak]

This PR remove strong dependency on external volumes.
All configuration can be done through env variables
It simplifies application deployment in an environment like kubernetes

Anyway it still work the old way.
We do not generate /etc/config.properties if it's already mounted

[olblak]

It seems that ci.jenkins.io is stuck on the wrong commit (c4563c6)
This commit don't exist anymore.

[rtyler]

@olblak #96 requires a persistent volume to be used. The k8s work will still support that yes?

[olblak]

In order to use #96
I was thinking today to update following projects:

1. Azure: Add a new shared disk named 'accountapp' within then same storage account than logs with 50Gb allocated
   we can update -> azure project
2. Accountapp: Configure new variables (electionCandidates, electionLogfile, electionOpen, electionClose) through env variables (with a separated PR)
3. Jenkins-infra: Add a new kubernetes resource called 'accountapp', with the same approach than Fluentd

[olblak]

In order to run rake test, I use a ruby docker image to run rspec tests.
Part of the tests, is to build and run a docker container in order to check installed packages,files,directories,...
That mean I need to do docker next to docker.
I made the assumption that docker group id is 982 in order to mount and use docker socket within the ruby container

[olblak]

I am closing this PR as I am splitting the content of this PR in several others.