FEATURE: Site settings defaults per locale

This change-set allows setting different defaults for different locales. 

It also:

- Adds extensive testing around site setting validation

- raises deprecation error if site setting has the default property based on env

- relocated site settings for dev and tests in the initializer

- deprecated client_setting in the site setting's loading process

- ensure it raises when a enum site setting being set

- default_locale is promoted to `required` category.

- fixes incorrect default setting and validation

- fixes ensure type check for site settings

- creates a benchmark for site setting

- sets reasonable defaults for Chinese

script/benchmarks/site_setting/bench.rb

@@ -0,0 +1,48 @@
+require 'benchmark/ips'
+require File.expand_path('../../../../config/environment', __FILE__)
+
+# Put pre conditions here
+# Used db but it's OK in the most cases
+
+# build the cache
+SiteSetting.title = SecureRandom.hex
+SiteSetting.default_locale = SiteSetting.default_locale == 'en' ? 'zh_CN' : 'en'
+SiteSetting.refresh!
+
+tests = [
+  ["current cache", lambda do
+    SiteSetting.title
+    SiteSetting.enable_sso
+  end
+  ],
+  ["change default locale with current cache refreshed", lambda do
+    SiteSetting.default_locale = SiteSetting.default_locale == 'en' ? 'zh_CN' : 'en'
+  end
+  ],
+  ["change site setting", lambda do
+    SiteSetting.title = SecureRandom.hex
+  end
+  ],
+]
+
+Benchmark.ips do |x|
+  tests.each do |test, proc|
+    x.report(test, proc)
+  end
+end
+
+# 2017-08-02 - Erick's Site Setting change
+
+# Before
+# Calculating -------------------------------------
+# current cache    167.518k (±12.1%) i/s -    822.983k in   5.000478s
+# change default locale with current cache refreshed
+# 174.173  (±16.7%) i/s -    845.000  in   5.015281s
+# change site setting    132.956  (±16.5%) i/s -    663.000  in   5.124766s
+
+# After
+# Calculating -------------------------------------
+# current cache    167.170k (±12.2%) i/s -    824.688k in   5.022784s
+# change default locale with current cache refreshed
+# 79.876  (±16.3%) i/s -    392.000  in   5.067448s
+# change site setting    129.085  (±13.2%) i/s -    636.000  in   5.032536s