message: Use primary styling on download / clipboard key actions
diff: @@ -363,10 +363,10 @@ export default React.createClass({
  <code ref={this._collectRecoveryKeyNode}>{this._keyBackupInfo.recovery_key}</code>
  </div>
  <div className="mx_CreateKeyBackupDialog_recoveryKeyButtons">
  - <button onClick={this._onCopyClick}>
  + <button className="mx_Dialog_primary" onClick={this._onCopyClick}>
  {_t("Copy to clipboard")}
  </button>
  - <button onClick={this._onDownloadClick}>
  + <button className="mx_Dialog_primary" onClick={this._onDownloadClick}>
  {_t("Download")}
  </button>
  </div>
  