Merge branch '12-example-in-documentation-does-not-work' into 'master'

Fixed documentation and preovided default value for database in JobManager

Closes #12 

Fixed it.

See merge request !2

doc/program.rst

@@ -15,10 +15,10 @@ submit a python script:
 .. code-block:: python
 
    import sys
-   from gridtk.sge import JobManager
+   from gridtk.sge import JobManagerSGE
    from gridtk.tools import make_shell
 
-   manager = JobManager()
+   manager = JobManagerSGE()
    command = make_shell(sys.executable, ['myscript.py', '--help'])
    job = manager.submit(command)
 

gridtk/manager.py

@@ -15,7 +15,7 @@ from distutils.version import LooseVersion
 class JobManager:
   """This job manager defines the basic interface for handling jobs in the SQL database."""
 
-  def __init__(self, database, wrapper_script = None, debug = False):
+  def __init__(self, database = 'submitted.sql3', wrapper_script = None, debug = False):
     self._database = os.path.realpath(database)
     self._engine = sqlalchemy.create_engine("sqlite:///"+self._database, connect_args={'timeout': 600}, echo=debug)
     self._session_maker = sqlalchemy.orm.sessionmaker(bind=self._engine)