add 2 new fields in ClJob

add attributes
cmd_line which is a string representing the command line
cmd_env which is a dict containing the environmenr needed to execute the
cmd_line

add unit tests to test CLJob
Merge branch 'develop' into feature_mongokit_ee_integration
add 3 new method in Status

- is_buildable : returns True if the Job which hold this state is ready
to be building all parameters have been sets, all environment nneeded to
execute the job must be prepare (create working directory,...)

- is_active : returns True if the status reflect a job which should be
	handle by the execution engine, from buildable and not teminal

- active_states : returns the list of Status handle by  the exec_engine
this is a class method
add tests for 3 new methods is_active, is_buildable and active_states