Seperate two packages for contrail-webui to contrail-web-core and …

 contrail-web-controller.
 2. contrail-web-core is the base package, when this pkg is installed then only
 login page comes if trying to login, then "Install feature package" message
 gets
 displayed.
 3. contrail-web-controller is the feature package for contrail-webui.
 4. So at run time new web feature package can be installed and uninstalled.
 5. All the new package path needs to be added in core config file.
 6. At init time, based on the package available, the static file directory
 registration, app to URL, job listeners etc. gets registered.
Changes in 'make dev-env' …
    1. if "make dev-env" is issued then it does build for current directory
    (contrail-web-core)
    2. If want to build for other features, then we can specify like
       "make dev-env REPO=webController,storage
    The options for REPO MUST be already available under config.featurePkg.
    3. Making a soft link of node_modules to all package directory.