added scan/scroll methods to client
added unit tests for scroll_search method
added unit tests for scroll_search method, removed index and type as args for scroll_search since they are set during scan_search
updated readme file with scan_search and scroll_search methods
fixed lint errors
Merge branch 'master' of https://github.com/BryanDonovan/node-simple-elasticsearch
Merge pull request #1 from enetzer/master

added scan/scroll methods to client