Jenkinsfile: parameterize variants & images to be built
Jenkinsfile: parameterize variants & images to be built

The variants and images to be built were hardcoded in
JenkinsFile. So if there was a need to add or remove
variants and images, the code needs to be changed. With
this change, a list of variant and images are defined
in Jenkins Environment, which are read dynamically in
JenkinsFile. So adding/removing variants and images do
not require code change.

Signed-off-by: Tariq Ansari <dad672abc2e4079f76b3a3bd368bb45008914527@luxoft.com>

Pelagicore/meta-pelux,Pelagicore/meta-pelux,Pelagicore/meta-pelux