Improve service symlink
Improve service symlink

At the moment, the symlink operation that happens during the DBus
environment setup in jiyuubot-launcher will fail silently on error. This
commit prints errors if they occur. Service prefixes are also the basis
for the test, in preparation for client activation.

Bob131/JiyuuBot-ng,Bob131/JiyuuBot,Bob131/JiyuuBot-ng,Bob131/JiyuuBot-ng