Fix gem building

Make sure gem can be build using target 'gem', even though doc generation might fail
fix error: call to 'ref' is ambiguous

compiler error on OS X
coordination: add option to jump into state-machines

by passing the argument :starting_state the user can choose
states in which a statemachine should start.


These states needs to be dinfed within the statemachine as:

prepare_jumpin("wall" => wall1, "pipeline"=> pipeline1)