fix Boost's linkage issues

[ashishraste]

Hi authors of aau_multi_robot,
You've a great package having ROS support, cheers!

I came across few build/linkage issues related to Boost library, while building adhoc_communication (alone) using catkin_make/catkin. Following is a short gist of it, which I found applies to a system having Ubuntu 14.04, gxx-4.8 or gxx-5, Boost 1.54 or 1.63.

1. Without having boost/format.hpp header inclusion in function.h header, Boost's format module isn't recognized.
2. Appropriate linkage of the Boost library has to be done in CMakeLists.txt of adhoc_communication.

Kindly review this commit for building this package on different build systems having different versions of Boost.