title: BOX v2 API for overwriting a file or checking one exists before trying to upload
body: <p>I'm new to the BOX API so am using v2 of the API. I am making REST calls natively from my app.</p>
  
  <p>I want to upload a file which may or may not have been previously uploaded. I know the parent folder ID and the file name. I need to either overwrite an existing file or at least make another call to see if the file already exists.
  I can see no way of doing either with the v2 API.</p>
  
  <p>I can upload files without problem. But of course I get an error if the file already exists.</p>
  
  <ol>
  <li>In v1 there was a way to specify an overwrite in the upload call. No such thing in v2 as far as I can tell. Am I correct? Will an overwrite flag get added back into the API?</li>
  <li>Given a file name how do I see if this already exists in a specific parent folder?</li>
  </ol>
  
  <p>To me this is fairly basic stuff so perhaps I am missing something reasonably obvious?</p>