Update docs generation to work with latest tools.mk

* The hand-written documentation has been moved from doc/ to docs/ so
  as not to conflict with generated edocs. .gitignore and rebar.config
  were updated to reflect this change.
* Added latest tools.mk which includes the upload-docs target for use
  in buildbot.
Merge pull request #54 from basho/bugfix/sdc/edoc-generation

Update docs generation to work with latest tools.mk

Reviewed-by: reiddraper