Give Command updates

Updates to the `give` and `item` commands to better emulate vanilla behavior. Consolidated `give` and `item` commands into one area to facilitate code sharing and implemented basic handling of vanilla style data tags (at least the ones that currently are supported by MCServer). Also updated Info.lua file with additional information and moved `item` command to its own permission node (`core.item`). Updated README.md file included.

These changes are building towards addressing mc-server/Core#89, but before I implemented something new I figured I should fix the old.
So, yes this does currently support all the vanilla syntax that I'm aware of, with one exception that I just stumbled on - that being vanilla lets you do: `cat:[String 1,String2,...]` without quotes around the individual string sections (I haven't figured out how to handle that case yet). This implementation requires quotes around the string sections (`cat:["String1","String2"]`), which I had thought vanilla did as well (according to the wikis it did), but turns out they're optional. As for errors, it executes in a pcall so it doesn't crash on invalid syntax, but at the same time the error messages aren't necessarily very descriptive as to the issue.

On your second note, yes it currently doesn't let you include `:` or `[` or `]` in the strings, which I knew, and am looking into, but since they were only three characters, I figured it be worth starting the process and getting input on the code and just note them as errata while figuring out how to handle the data tag better (not letting perfection stand in the way of improvement, basically).