Working up to version 2

Added PlotManager to keep track of plot information and sign
information.
Added PlotListener and IEconomy

Still need to add some checks, when breaking/placing signs. Like
permissions.
Added place/break permission checks and min/max cost checks

Added IPlotPermission interface.
Added checks (and TODOs) to PlotListener.
Added some configurations to IPlotWorldConfig.
Added worth methods to Plot.
Added more checks and TODOs to PlotListener.

Added plugin package with a bunch of implementations of the interfaces
in the plots package.
Added PlotControl class for commands
Added buy- and define methods to PlotControl
Forgot to add permissions to PlotPermission class
Added sendWorth and sendRegionCount methods
Added PlotCommand class that has all commands

Added PlotCommand class in plugin package, that uses PlotControl in
plots package.
Added Permission class that has all permissions. PlotPermissions uses
them.
Added plugin.yml file. And default config.yml file.
Fixed some small issues.

Still need to add some default IPlotWorldConfig that is used for
non-existing IPlotWorldConfig. And other things.
Command help cleanup
Added multi world support. Still needs testing

Added multi world support. Still needs testing.
Generates global config and accepts world specific configs.

Fixed reserve free regions.
Fixed sign placement. Allowing trailing space.
Changed a lot involving plot- and sign-data

Multi-world support is working properly. There's 1 default configuration
file, that is used in case of missing world configuration files. But
also in case of missing fields in a world's configuration file.

Plus some other small fixes
Changed file structure, now only 1 occurance of world name

Moving some classes and packages
Can't cause homeless if free regions are reserved for homeless

Added potential homeless check to delete/sell/buy.
Cleaned up the define/redefine commands.

Added a bunch of comments for clearance
Fixed error in PlotWorld class
Merge pull request #2 from ghost/version2

Version 2 alpha, here we go! Thank you https://github.com/lalo5