New feature: HTTP proxy config using HomeServerConnectionConfig

[unclejay80]

With this change it is possible to configure a HTTP proxy (hostname & port) from an app which integrates the SDK

Pull Request Checklist

• Pull request is based on the develop branch
• Pull request updates CHANGES.rst
• Pull request includes a sign off

Signed-off-by: Jürgen Wischer me@unclejay.de

[bmarty]

LGTM.
I've made a few comments.
Regarding the proxy usage, maybe it should also be passed when opening a url connection at those places:

• matrix-android-sdk/matrix-sdk/src/main/java/org/matrix/androidsdk/db/MXMediaDownloadWorkerTask.java

  Line 740 in 27c30ba

  connection = (HttpURLConnection) url.openConnection();

• matrix-android-sdk/matrix-sdk/src/main/java/org/matrix/androidsdk/db/MXMediaUploadWorkerTask.java

  Line 299 in f967dab

  conn = (HttpURLConnection) url.openConnection();

  
  And maybe

• matrix-android-sdk/matrix-sdk/src/main/java/org/matrix/androidsdk/rest/client/UrlPostTask.java

  Line 66 in f967dab

  HttpURLConnection conn = (HttpURLConnection) url.openConnection();

[bmarty]

I think it's ok to pass the HomeServerConnectionConfig to whoever does network requests.
Please just revert the change on the DataHandler as per the comments.
First I thought about just passing the Proxy, but we may need other parameters. I'm just vigilant, because it also contains the access token, which is quite a sensitive data and I do not want it to be used by mistake. But for the moment it's ok.

[bmarty]

LGTM, thanks for the update