Changelog entry for #234 and #235
OAuth1Client: Allow to set a request body

The parameters will be appended to the URL instead. Note that the body is unsigned (i.e. no OAuth request body hash is included)!
OAuth1Client: Allow to set a content type
change log entry for #235

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Update CHANGELOG
Merge pull request #237 from cschramm/oauthcontenttype

OAuth1Client: Allow to set a content type
Merge commit '9819f4452c6319368cd06eb949ebe111586ea9a8'

* commit '9819f4452c6319368cd06eb949ebe111586ea9a8':
  Update CHANGELOG
  OAuth1Client: Allow to set a content type
  OAuth1Client: Allow to set a request body
  Changelog entry for #234 and #235