Added "Mark entire Volume as Unread" option.
- Revised imageTemp.getPath check logic
  (Added a java.net.URLDecode.decode function to handle special characters on filepaths. I dunno why but big images with special chars don't work on my ICS, sample pics: Hataraku Maou-sama! Vol.01->Novel Illust->2nd pic and Campione! cover pic.)
- View Changelog on Version Click, it opens the file /res/raw/changelog.txt
  (.. and added changelog.txt file on /res/raw/, which needs to be updated each release.)
Merge pull request #99 from yaminorito/master

Mark entire Volume as Unread, revised imageTemp.getPath, and View Changelog