'fjl-mutable' methods and functional versions of `Object` statics

New additions

• Re-instantiated flip3, flip4, flip5 - Turns out there was a use for these after-all (fjl.native).
• Added native which includes all the
  static methods that live on Object though
  flipped and curried.
• Added 'fjl-mutable' as part of source. All methods of 'fjl-mutable' now
  live directly on 'fjl' and are defined in 'fjl/objects/defineProp' (or more directly in src at './src/objects/defineProp').

Deprecations

• Marked hasOwnProperty as deprecated (as property
  is not really in the haskell prelude and is a bit
  of an oddity when it comes to the functional mindset).

Development changes.

• Updated 'dev-deps' to use latest babel.
• Updated gulp version
• Updated .travis* file.
• Moved './gulpfile.js' to 'gulpfile.babel.js' in order to easily use es6 imports.