Add option to change between the 3 upload methods

[ninjadudexp]

From what i was told there should be 3 options for update type

the CLI options: -u/--update-epub, ( this updates only the chapters missing i believe) -U/--update-epub-always ( This will update the file not delete, but also retain old chapters i think but will overwrite chapter changes i believe) --force ( i think this just deletes and redownloads)

  -u, --update-epub     Update an existing epub(if present) with new chapters.
                        Give either epub filename or story URL.
  -U, --update-epub-always
                        Update an existing epub(if present) even if there
                        aren't new chapters.  Give either epub filename or
                        story URL.
                        setting.
  --force               Force overwrite of an existing epub, download and
                        overwrite all chapters.