Created creative tab

Made the custom creative tab, currently uses the icon of the
blastfurnace block.
Moved blocks and items to new tab

Also cleared up the imports
Added missing GPL3 license

Forgot I don't have my laptop set up to automatically add these in, the
new creative tab class should now comply with the license.
Merge pull request #31 from Hanse00/feature-custom-creative-tab

Feature custom creative tab