Added Java Driver

As recommended on the mailing list by Slava Akhmechet, I'd like to add a java driver.

This is more typed than the existing one and adds functionality for java 8 lambdas making overall syntax more terse. See the github page and docs for more info.
Changes based on review
Add python and ruby doc changes
Closes #375
Add author credits
Merge branch 'pr/390' - add @npiv Java driver
Add cookbook entry for returning query as string
Closes #354
Fix python docs
Update unpivot example recipes
Fix io for r.literal
Clarify how 'not' handles nonbool values
Merge pull request #396 from rethinkdb/michel_python_docs

Fixes for the python docs.
Merge branch 'issue-374-not-nonbool'
Closes #374
Style change. Closes #316
Merge branch 'issue-316-unpivot-keys'
Fix typo (closes #392)
Add quickstart and tech comparison images
Change to use new CSS class
Changing back to pure Markdown
Image shuffling based on feedback
Deleting technical comparison image