Currently installer gets a list of commands to be executed from the deploy code.
However, some of the commands can fail because file can be in use (e.g. can not remove old dll because it is used by browser).

We need to:
  a) Try to use tricks to workaround these issues. E.g. rename file and then delete instead of deleting it directly.
       (Rename part will work)
  b) Show user dialog explaining how he can fix problem (file in use, etc.)
  c) in case of error - either retry later or report install failure