signal: check that signal signature is always valid (tuple or anyargs)
signal: check that signal signature is always valid (tuple or anyargs)

Change-Id: I2b3d639067cc10c0b446182c22de72794daeb52f
Reviewed-on: http://gerrit.aldebaran.lan/26644
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: cgestes <ddb78fe00abb42f91254c16a0860e38eb0781789@aldebaran-robotics.com>

aldebaran/libqi,aldebaran/libqi,bsautron/libqi,vbarbaresi/libqi,aldebaran/libqi