Add more structure for adapters.

I foresee more adapters being created (i.e. hash). To enable the easy
addition of these adapters I added an adapters folder. I also changed
all of the require statements.
Update README.md

Remove extra paragraphs from readme
Update LICENSE.txt
Merge pull request #3 from dhahn/add_structure_to_adapters

Add structure to adapters
Merge branch 'master' of github.com:dhahn/tablinate
Merge branch 'master' of github.com:unholydh/tablinate