Fix gemspec

weather-model.gemspec

 # coding: utf-8
 lib = File.expand_path('../lib', __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require 'weather/model/version'
+require 'weather-model/version'
 
 Gem::Specification.new do |spec|
   spec.name          = "weather-model"
-  spec.version       = Weather::Model::VERSION
+  spec.version       = WeatherModel::VERSION
   spec.authors       = ["Ivan Lan"]
   spec.email         = ["mumumumushu@gmail.com"]