Align DCAE plugin builds similar to ccsdk plugins.

Current plugins are generated based on release specific folder and has below structure

k8splugin/1.7.2/k8splugin-1.7.2-py27-none-linux_x86_64.wgn
relationshipplugin/1.1.0/relationshipplugin-1.1.0-py27-none-linux_x86_64.wgn
clamppolicyplugin/1.1.0/clamppolicyplugin-1.1.0-py27-none-linux_x86_64.wgn
{{dcaepolicyplugin/2.4.0/dcaepolicyplugin-2.4.0-py27-none-linux_x86_64.wgn }}

CCSDK plugins are pushed into nexus/raw under simpler structure

plugins/pgaas-1.1.0-py27-none-any.wgn
plugins/dmaap-1.3.5-py27-none-any.wgn
plugins/sshkeyshare-1.0.0-py27-none-any.wgn
plugins/helm-4.0.0-py27-none-linux_x86_64.wgn

This will avoid discrepancies on how plugins are loaded in bootstrap and also having need to create release specific folder for DCAE plugin.