increased maven compile version to 1.8 and removed redundant plugin
increased maven compile version to 1.8 and removed redundant plugin

Signed-off-by: Victor Ursan <3afdf24b104189ac4177a1346078f9d352c70c06@hpe.com>

CloudSlang/cloud-slang,CloudSlang/cloud-slang,CloudSlang/cloud-slang,CloudSlang/cloud-slang