[#3] Code from eralsticsearch.
[#3] Removed unncessary code.
[#3] Simplified code, deleted a whole bunch.
[#3] Removed io:formats. Don't create a pool if it doesn't exist.
[#3] Removed log folder.
[#3] Replaced request and response records for maps.
[#3] Removed duplicated guards from make_request function.
[#4] Replaced usage of poolboy for worker_pool.
[#4] Removed poolboy related files.
[#4] Updated return value from do_request.
[#4] Refactored modules into API module and worker.
[#4] Replaced state record for map.
[#4] Removed unused types. Moved all types from .hrl to .erl files.
[#4] ''Fixed'' elvis comments.
[#4] Added elvis.config file.
Merge pull request #5 from inaka/jfacorro.4.start.from.erlasticsearch

[#4] Use erlasticsearch as a reference and adapt it to work with HTTP