implementation of initial_scale service option (issue #116)

Signed-off-by: Emil Kroymann <emil.kroymann@gmail.com>

refactored initial_scale feature according to the suggestions of dnephin

Signed-off-by: Emil Kroymann <emil.kroymann@gmail.com>

b/f: test case had side effects visible for other test cases

Signed-off-by: Emil Kroymann <emil.kroymann@gmail.com>

test cases for initial scale feature

Signed-off-by: Emil Kroymann <emil.kroymann@gmail.com>