Cleanup & Proper usage of NIO

[jacobtread]

Cleaned up the files making them more readable (Slimmed down path resolutions and added method getMinecraftPath as an alternative to getWorkingPath which replaces a lot of reused calls)

Moved getWorkingPath code to the field workingPath in net.hypixel.resourcepack.pack.Pack so that it is only created once instead of re-creating it every call (this was also done for the getMinecraftPath method)

Fixed incorrect usage of nio Paths being converted to io files then accessed instead of using the Files interface for nio. This also includes the use of Collections.singleton when writing the file as this can be replaced with a call to getBytes(Charset)

[Fallstop]

It would be great if this would be merged.