Use user-defined animation duration instead of fixed time

jQuery supports 'slow' (defaults to 600 ms), 'fast' (defaults to
200 ms) and default (400 ms). The importand advantage is: These can
be changed by the user. A constant number can not.

Change-Id: I590a7d16062bd7c89692ca14e9da8f7f927ddef2
Merge "Use user-defined animation duration instead of fixed time"