Import esrefactor and its dependencies (estraverse, escope).

This will be used in the identifier highlight demo.

https://code.google.com/p/esprima/issues/detail?id=414
Identifier highlight demo: take the scope into account.

This is done using esrefactor library (which further relies on escope,
another micro library to analyze identifier scope).

https://code.google.com/p/esprima/issues/detail?id=414