Simplify and unify get-text method
Decomplect core functionality further

Move extractors into their own namespace, pending further development
Create Util namespace for wrap-paragraph, similar functions.
Add type hints (why not?)
Test scaffolding for core functionality
Import Java classes the Hickey-approved™ way
Make changes suggested by code review

* Change if-let in core ns get-text fn to an it
* Make get-text use ArticleExtractor rather than DefaultExtractor
  when extractor is unspecified
* Add ArticleSentencesExtractor to extractors ns
get-text now uses multiple bodies instead of if
Merge branch 'simplify-get-text' of https://github.com/nickbarnwell/boilerpipe-clj into nickbarnwell-simplify-get-text
Merge branch 'testing'
Add more tests.
Eliminate reflection warnings.

Remove unnecessary type hints.
Reorder function bodies for get-text.