Update README.md

Corrected missing word
Fixed README.md
Changed CMakeLists.txt with the following:
- All libraries but singleton are compiled as MODULE, not as shared
- Use capital letters for GAZEBO_LIBRARIES variable
Update README.md
Merge pull request #52 from DanielePucci/patch-1

Update README.md
Fixed bug in analog server names for force torque, it's a patch, better to fix it in another way...
Implemented positionDirect interface and group positionMove
Update README.md
Merge branch 'master' into development

Conflicts:
	CMakeLists.txt
	src/gazebo_plugins/ForceTorque.cc