Minor cleanup

No need for this here since .addXp() also does xpCheckSkill()
Also, thank you @bm01 for the cleanup! :)
Removed some deprec(i)ated calls to Users.getProfile()
Fixed /addlevels not working on offline players
Fixed /addlevels all throwing NPE because of Smelting
Removed use of Users.getProfile()
Fix NPE on startup relating to old party files without an xp share mode
set.
Fix issue where the vanilla XP boost for smelting would be called
regardless of who took the item out of the furnace. Not only does this
fix the exploit, it also fixes an NPE that could occur if the player who
lit the furnance was offline when someone else extracted the items from
it.
Localize a string I missed last time...
Locale file updates.
Forgot to add this to the changelog.
This is a much better way to work with our commands dynamically. It
allows for localized description strings, aliases, etc.

With this addition, our "ugly alias" method in CommandPreProcessEvent is
no longer needed, nor is our alias map.

This also makes us more friendly with Essentials - if Essentials is
enabled, the /repair command will be changed to /mcrepair for
compatibility reasons.
Rework /addlevels to use the built-in Bukkit command stuff.
Having an option to disable commands from the config was a bad idea that
encouraged lazy admins. 

NOTE: If you were using these config options instead of relying on
permissions, you will need to reconfigure these commands to be disabled
via permissions.
Refactoring of general commands - the prior package structure made no
sense.

New package structure splits commands into those normally reserved for
admin use and commands normally available to all players.
Removed redundant permissions check for skill commands.
Remove unused imports.
Apparently our ItemStack can be null here.
Fix bug in previous dev build that would make mcMMO never drop items...
Add back the descriptions to plugin.yml for documentation purposes.
Changelog update.
ACTUALLY fix the NPE this time.
Updating permissions for the /mcgod command.