Fix - changed IMAGE_VERSION env. variable default value

[Agnul97]

The IMAGE_VERSION environment variable default value was set to "latest". This change will simplify the deployment of future Kapua versions because before this fix a manual modification of such variable was needed in order to deploy specific versions of the project.
Furthermore, the deployment script has been modified to log the current value of that variable, in order to be more clear with the specific versions that it is in deployment

[codecov]

Codecov Report

Merging #3779 (13bdca5) into develop (fd877d7) will decrease coverage by 8.88%.
The diff coverage is 0.00%.

❗ Current head 13bdca5 differs from pull request most recent head 8b8ea30. Consider uploading reports for the commit 8b8ea30 to get more accurate results

@@              Coverage Diff              @@
##             develop    #3779      +/-   ##
=============================================
- Coverage      49.19%   40.31%   -8.88%     
+ Complexity        26        6      -20     
=============================================
  Files           1865     1866       +1     
  Lines          35275    35297      +22     
  Branches        2786     2786              
=============================================
- Hits           17352    14229    -3123     
- Misses         17003    20066    +3063     
- Partials         920     1002      +82     

Impacted Files	Coverage Δ
...pse/kapua/job/engine/commons/logger/JobLogger.java	0.00% <0.00%> (ø)
...resources/v1/resources/UserCredentialFiltered.java	0.00% <0.00%> (ø)

... and 551 files with indirect coverage changes