Removing prototypal i18n code

[ErisDS]

refs #16, #17, #18, #19, #20, #21, #3801

• This code was a prototype system built when Ghost was still a prototype.
  It was never fully implemented and hasn't actually worked for ages.
• Now that the admin is in Ember, it's likely we'll need a very different
  system.

[hswolff]

You forgot three instances where node-polygot is used:

Ghost/core/server/index.js

Line 8 in e6bb7c4

Polyglot = require('node-polyglot'),

Ghost/core/server/index.js

Line 208 in e6bb7c4

Polyglot.instance = new Polyglot();

Ghost/core/test/unit/server_helpers_index_spec.js

Line 9 in e6bb7c4

Polyglot = require('node-polyglot'),

[ErisDS]

DERP.