Bugfix: not all borders are written when specific borders specified

[pscheit]

testcode:

    $cell = $row->addCell(400, array(
      'borderRightColor'=>'efefef',
      'borderRightSize'=>40,
      'borderBottomColor'=>'efefef',
      'borderBottomSize'=>40,
    ));

displays only rightBorder but not the bottomBorder.

Sorry for no unit test. Would you prefer the XMLWriter to be injected and then the xml output tested or mocking the XMLWriter and testing the behaviour with expectations? (difficult with PHPUnit only, I would suggest using mockery)
Unfortuately I cannot write the unit test right now, but still hope this bug will be fixed

[pscheit]

hey guys, can you merge that? Something missing?

[Progi1984]

@pscheit Two points :

• Could you push your pull request to the develop branch and not the master branch ?
• Could you add a line in Changelog.md, please ?
  And I will merge your commit after. Thanks

[pscheit]

okay now its here #327