* Fix aria2c failed to start after change daemon user, issue #2985;
* Change default download dir;
* Clear exist log file when aria2 start;
* Add log level option;
* Change dir owner when start.

Signed-off-by: Hsing-Wang Liao <kuoruan@gmail.com>

add aria2.log and replace logger -t ARIA2C 'Restarting aria2s service'  with logger -t ARIA2C 'Restarting aria2c service' :D :p

Signed-off-by: Hsing-Wang Liao <kuoruan@gmail.com>

This update is from #2961, thank @hostkit.

Signed-off-by: Hsing-Wang Liao <kuoruan@gmail.com>

* Add config file.
* Add init.d file.

Signed-off-by: Hsing-Wang Liao <kuoruan@gmail.com>