add proprety dir to project

with the getter and setter to set and get the directory of the project.
the property dir can be assigne only once. after that it become unmtable
if we try to mutate it a MobyleError is raised

add corresponding unit tests
add proprety dir to job

with the getter and setter to set and get the directory of the
job. The property 'dir' can be assign only once. after that it become
unmutable. If we try to mutate it a MobyleError is raised

add corresponding unit tests
add getter id  for "private" attribute _id to project

add corresponding unit tests
add test for property "id"
improve documentaion for create_time
project is now required to save a Job

add project.id to created jobs
modify the structure of Jobs

add field _type to allow inherited queries (fixed with mongokit > 0.9.0)
owner is not anymore a basetring but a dict with 2 keys
owner' : {'id': ObjectId, 'klass': basestring},
an owner can be a Project or WorkflowJob
debugging
remove _type attribute for debuging
reorganize status

add new status to avoid monitor to do some jobs twice
for instance there was no distinction between a job ready to by build
and currently building (handle by buid actor)
so the monitor generate a buildactor for a job and if the building
action is longer than the monitor, the monitor will generat a new
building actor for the same job.

so now there are status to tell
 - a job is ready to be process by an actor TO_BE_BUILT, TO_BE_SUBMITTED
 - a job is currently process by an actor BUILDING, SUBMITTING, UPDATING

update doc and test acording to this new status
modify structure for owner propoerty

due to a bug in mongokit see
(https://github.com/namlook/mongokit/issues/137)
the property of owner is set to dict instead of using netsted structure