Apply Clojure style guide

Eliminate whitespace: move end-parens to same line as statement; comma in parameter list.
Eliminate unnecessary (let).
Combine :requires per style guide
Add endpoints: taxonomy, combined, image_extract, image tag
Add macro definitions for new endpoints
Merge pull request #2 from daveliepmann/master

Apply Clojure style guide
Add endpoints: taxonomy, combined, image_extract, image tag