title: GIT: change commit date to author date
body: <p>Is it possible to change the commit date from my commit to the author date?</p>
  
  <p>I adapted some commits and now the dates are all the same. I want to set it back to the old dates (or the author dates). Is this possible?</p>
  
  <p>I am using Sourcetree so I have the git command line but I am not a pro at that. My external repository is bitbucket.</p>