title: Is Azure Blob storage transactional?
body: <p>As the title states is Azure Blob Storage transactional?  I have a two scenarios:</p>
  
  <p>1) I need to insert/modify two files. They need to be all or nothing so if one fails, none get inserted/updated.</p>
  
  <p>2) When updating how is contention handled? Lets say I have file.txt. Two users at the same time want to update the content of that file. What happens in this situation?</p>