Parallel builds

[zamotany]

• if -A, --app is specified, by default disable server compilation unless --server flag is passed

• support building single app using -A option
• vendor DLL bundle config
• add progressHandler to vendor DLL config
• support building vendor DLL bundle
• support bailing from vendor DLL build if it's valid/ok
• don't compile client/server webpack config if compiling vendor
• working in dev
• backwards compatibility support for src/vendor.js file
• backwards compatibility support for gluestick-config-legacy
• working react and redux devtools
• test
• is --client option needed for -A? if not is it obvious that server won't be compiled?
• custom chunks plugin to append data instead of overwriting
• docs
• don't compile client config if building server
• support dev and production vendor dll builds
• test on internal project