Merge pull request #480 from ovatsus/master

Improve error reporting in the Freebase provider
Fixes PUrify for Mono to keep replace only the path part of the URI.
Merge pull request #482 from diegofrata/urislashes3

Fixes PUrify for Mono to fix only the path in the URI.
Remove ;
Http Improvements (closes #296)

* Add stronger typing to Http parameters. (from http.fs project)
* Respect character set header in Http responses. (from http.fs project)
* Allow to don't throw on Http error. (from http.fs project)
* Allow to customize the http request by passing a function.
Check for repeated headers
More http improvements

* Rename some things in Http to avoid name conflicts in DU cases between request/response
* Add more headers
* Port integration tests from http.fs
More http improvements

* Rename some things in Http to avoid name conflicts in DU cases between request/response
* Add more headers
* Port integration tests from http.fs
* Allow to override the response encoding
* Added RequestStream and AsyncRequestStream methods to Http to allow accessing the response stream directly (closes #210)