Re-factored the extraction methods to reduce duplicated logic. This *has* changed the public api of the extractWebJarTo slightly in that the WebJar name is no longer the top level folder for the extraction. This is consistent then with the original extractWebJarTo method and could potentially re-use any cache logic. It is also consistent with the merging strategy that we want to see with node_modules.
Removed some compilation warnings.
Added a means to extract an immediate sub folder of a WebJar’s contents
Merge pull request #33 from huntc/node_modules

Node modules and extractor re-factorings