Add more types to ASTNodeKind. Refactor common instantiation code.

Summary:
Add support for CXXCtorInitializer and TemplateArgument types to ASTNodeKind.
This change is to support more matchers from clang/ASTMatchers/ASTMatchers.h in the dynamic layer (clang/ASTMatchers/Dynamic).

Reviewers: klimek

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1143