Cleaned README
Update README.md

Added some ld/yarp troubleshooting I had while trying to compile it from source code.
Update README.md
fixed use of deprecated boost function
Merge pull request #44 from robotology/issue43

fixed use of deprecated boost function
1. editing the CMakeLists for adding the following libraries: boost-system sdformat protobuf. 2. Removed Mutex and replaced with yarp mutex. 3. removed unused ace include. 4. In CMakeLists added explicit include and link to libraries
Update .travis.yml to include boost system compile time dependecy to test both Debug and Release compilation
Fixed missing yarp/os/Mutex.h header
Substituted yarp::os::Mutex with yarp::os::Semaphore for compatibility with yarp 2.3.22
merged singleton with mac-osx