(TK-117) Add external API docs

Add some external API docs in the doc folder which detail how
to make requests using the Java and clojure clients.
(TK-117) Address PR comments

Expand discussion of the `close` function for clojure clients and
the `close` method for Java clients. Add examples for making
requests with various types of clients. Fix wording/typos.
(TK-117) Add javadoc strings

Add javadoc strings to each of the user-facing Java classes, and
reference those javadoc strings in the documentation on the
Java client.
(TK-117) Address further PR comments

Make a number of minor cosmetic changes to address PR comments.
Document constructors for the SimpleRequestOptions class.
Merge pull request #28 from fpringvaldsen/TK-117-external-api-docs

(TK-117) Add external API docs