[B+C] Added Locale API. Adds BUKKIT-2220, BUKKIT-4507

##### The Issue:
The Bukkit API has no possibility to access the Settings from the Client. This PR adds a LocaleManager for Plugins and a Event which gets fired when the Client changes its Settings.

##### Justification for this PR:
Adding Language and other Settings to the API will help Plugin Developers providing more customised Texts for the Players.

##### PR Breakdown:
Adding a new Method for calling the PlayerSettingsChangeEvent out of the EventFactory
Making EntityPlayers locale public so the CraftPlayer can access it

##### Testing Results and Materials:
For testing i made a Little Plugin which loads in two Languages and greets the Player based on his language Setting. Source: https://github.com/geNAZt/LocaleTestPlugin

##### Relevant PR(s): 
B-983- https://github.com/Bukkit/Bukkit/pull/983 - The new API for the Locales and Settings
CB-1286 - https://github.com/Bukkit/CraftBukkit/pull/1286 - Extended the EventFactory and the CraftPlayer to get the Locale and Settings

##### JIRA Ticket: 
BUKKIT-2220: https://bukkit.atlassian.net/browse/BUKKIT-2220
BUKKIT-4507: https://bukkit.atlassian.net/browse/BUKKIT-4507