Find a way to configure Tern Modules that are default for Nature Adapters defined on a project

A new extension point attribute defined for ternAdaptToNature element in ternNatureAdapters.exsd schema - default modules.
This new attribute allows to specify a comma-separated list of Tern Modules (Libs and Plugins) that are to be loaded by default in Tern Project
in order to provide content assist and validation without a need of manual project configuration.

Signed-off-by: vrubezhny <vrubezhny@exadel.com>