changed quotes to omit cmake warning

Name of maintainer is literally copied into package.cmake (in build/*/catkin_generated)
and quoted by double quotes. Hence, the maintainer name shouldn't
contain double quotes or catkin should correctly quote them for cmake...
test case for if/unless including floating point numbers

floating point expressions not equal zero should be evaluated as True
unified if/unless handling, correctly handle floating point expressions
test-case for recursive evaluation of properties
recursive evaluation of properties
test-case for recursive definition of properties -- should be catched