Don't crash when converting exception backtraces using Syck
Merge pull request #9 from arkadiyt/master

Don't crash when converting exception backtraces using Syck
Fixing an error where eager_autoload would fail, fixing an off-by-one error in forking executor that would allow one more worker than intended, and fixing a problem where we would poll for a task even when we we did not have workers to work on it, which would risk a needless timeout. Also added tests for the above.
Removing dead code from workers
Adding comment to detail the contract for flow_futures
Merge branch 'master' of https://github.com/aws/aws-flow-ruby
Bumping version for pushing the PR to rubygems
Made many changes and additions to the API docs. Changed `@!visibility private` tags to the more modern `@api private` tags.