Improve workflow generator.
Improve readme file with build instructions.
Do not store plugin binary in ElasticSearch (as it manages all as base64 binary and creates a lot of overheads in ES)
Fix new plugin management.
Merge branch 'develop' of https://github.com/alien4cloud/alien4cloud into develop
Cleanup plugin management (remove old fetch context that is now unused).
Move dagre-d3 dependency out of codebase.