tests: Make test_flushing_changes_to_shadow test something

Change-Id: Ie525af0222833e643b2e575a3aaa9ffae078278c
main: Speed up waiting for termination of daemons

This commit modifies command like 'mfschunkserver stop' or
'mfschunkserver kill' to check for existance of the process after
sending the signal 10 times per second instead of once per second.

Change-Id: Ifcbefbc83634fee559694bc8667f86e9b9d08515