olsrd-mdp now uses commotion/serval plugin to sign packets, instead of linking to serval library
removed all serval dependencies
added commotion_sock param to olsrd-mdp
change FILENAME_MAX to PATH_MAX
Be more defensive in writing to the sig buffer
Merge pull request #16 from hawkinswnaf/serval-plugin

Be more defensive in writing to the sig buffer

tested by areynold, dismantl
First attempt to fix #17.