Merge pull request #51 from gabelevi/fb-harmony

Add type annotations for ArrayPatterns and ObjectPatterns.
Parsing type aliases
Actually type aliases should be source elements. This means things like

    if (true) type foo = number

shouldn't be allowed
Switch to using (expect|match)ContextualKeyword
Merge pull request #58 from gabelevi/alias

Parsing Type Alias
Parse interfaces
s/parseParametricTypeAnnotation/parseTypeParameters/
Support rest parameter type annotations
Merge pull request #59 from gabelevi/interface

Parse interfaces
Merge pull request #60 from gabelevi/rest

Support rest parameter type annotations