[gpprofile.rb] add many extra members (e.g. staff)
add new script add-member.rb

This script adds specified member(s) to "members" table.
[gpupdate.rb] now use local_path on DB as dest_path to download.

So far, dest_path is presumed according to only the type of image every time.
But this occurs problems when mediainfo changes ext.name of image file after downloading.
In this case, dest_path differs actual file name.

Now, when local_path has already been registered on DB, this path is used as dest_path.
[lib/dbmodels.rb] now avoid creating 0-byte file when response body is null.
[lib/dbmodels.rb] avoid downloading fallback image when original image has been downloaded.

When ext.name of fallback image differs that of original image, script could not tell if
it should be download or not.
Then
  - add :fallback parameter to option
  - when :fallback is true, check maximum file size of not only dest_path but also all files with same basename.
[some files] rename variable for debug option and refactor how to use it.

  rename $debug to $opt_debug
[gpupdate.rb] add video's orientaion by the result of mediainfo

  - the value indicates rotation degree as exif format:
      1: Horizontal (normal)
      2: Mirror horizontal
      3: Rotate 180
      4: Mirror vertical
      5: Mirror horizontal and rotate 270 CW
      6: Rotate 90 CW
      7: Mirror horizontal and rotate 90 CW
      8: Rotate 270 CW

  - if the video has no data about rotation, the value is set to NULL.
new file:  oneshot/set-video-orien.rb