Deleted host-dependent environemnt file (.classpath, .project)
Supported wifi only mode

Updating/Downloading can be done only through Wifi.
(Preference is supported for this.)
User can change category of AppWidget in runtime through button in the widget.
Big refactoring to support various features regarding feed-contents(downloaded file).

Refactoring
- Listener management
- Code/File rearrangement.
- ContentsManager is newly introduced.
    : supports monitoring feed-contents-change.
    : uses human-readable channel directory instead of using just 'number' as directory name.
Used standard way to configure AppWidget.

In some devices AppWidget cannot be added.
By using standard way, compatibility is improved.
Supported multiplel selectdion when choosing predefined channels. (Not tested enough)
Fix bug : fix message like '-1 items are deleted'.

This should be shown as '0 items are deleted'.