[#33] Code clean up

* Fix lint issues reported by eastwood
* Move `prn` calls to TODO
* Don't delete the uploaded content after finishing the upload, this can
  be helpful when trying to debug problems
[#33] WIP - Upgrade libraries, refactor configuration loading

* We were loading the configuration using UploadConstants.properties,
  now all the config needed is in appengine-web.xml
* Upgrade the libraries to the latest published versions
[#33] WIP - Fixes bulk upload

TODO:
* Add acl-public to `upload` function when the uploaded file is an image
[#33] Fixes report invalidation, incorporates code review from @jonase
[#33] Make images/* public read by default
[#33] Adds missing response call
[#33] Notify server after succesful upload
[#33] WIP - Fixes report generation, adds validation on XLSX import
[#33] Fixes reference to RAW DATA import, adds Message on errors

* If the validate methods finds errors in the RAW DATA, we create a new
  `Message` using Remote API
[#33] Update version
[#33] Update Clojure version
[#33] Exclude joda-time from s3-aws lib dependency

* Hint provided by `lein deps`
Merge pull request #34 from akvo/feature/33

Refactor bulk upload plus new configuration