remove extra spaces
remove __all__
relax constraint on rule signature

it could be possible to add some extra parameters in definition of
rule function
the first parameter must be job
add more function rules, for testing framework
transform mob2exec in package
add  execution systems

set up the framework to handle the exexcution systems
the executions systems must inherits form ExecutionSystem abstract class
and implements run, get_status and kill methods.
to take in account in the mobyle these class must be registerd via the
decorator execution_systems.register

the class provide by mobyle will be placed in
mobyle.mobyle_execution_engine.systems

the mmobyle administrators can be extend mombyle with thier own classes
placed in execution_systems
set framework to route jobs