Automatic retry should have shorter wait time options

[doneykoo]

Your DownThemAll! and Browser Version and Language and Operating System

DTA 3.0.8 Firefox 54.01 Chinese Win10

Expected Behavior

Allow user to set preference to use Automatic retry for like 5 seconds after task got some error (like Server error)

Actual Behavior

Automatic retry preference only allows options longer than 1 minute.

Steps To Reproduce

try to download a big file (about 500MB) in Unity website: http://download.unity3d.com/download_unity/d3101c3b8468/Windows64EditorInstaller/UnitySetup64-5.6.3f1.exe The task easily got error, however I have to wait for more than 1 minute for it to retry, instead of choosing to wait shorter time. Actually the task can always correctly resume downloading after 5 seconds.