Made Jobs sharable between executions

Before, running a new workflow would not use jobs from previous workflows, not
even from the same workflow version.  Now jobs exist outside workflow
executions. Combined wit using the original module signature, this makes it
work better as a cache.

core/interpreter/job.py:
  - Jobs now exist outside workflows, but workflows still reference jobs.
  - Renamed modules -> jobs

core/console_mode.py: Modified job manager method names
gui/job_monitor.py: Modified job manager method names
Merge branch 'master' into job-cache
Set default job name to module class name

core/interpreter/job.py:
  Set default job nasme to self.__class__.__name__

Renamed _running_Workflows -> workflows
  gui/application.py
  gui/vistrail_controller.py
  gui/vistrails_window.py
Added method for persistent caching of outputs using jobs

Adds persistent caching of outputs for any module using new
control parameter job_cache

core/modules/vistrails_module.py:
  Added job_cache control parameter and checking/setting job cache for
  modules that use it.

gui/module_iteration.py: Added gui to set job_cache
Renamed ModuleIteration -> ModuleOptions

Because it now contains non-looping options
Also fixed issue with saving

gui/module_iteration.py -> gui/module_options.py
gui/pipeline_view.py: Changed action name
gui/vistrails_window.py: Updated imports
Loads packages from pkg_resources entry points
Merge branch 'master' into 'pkg-as-setuptools-plugins'
Fills in _available_packages early
Merge branch 'master' into 'pkg-as-setuptools-plugins'
Fixes bug with nested packages
Don't check package structure for plugins
Removes unused printVersion()
Adds --version
Fixes vistrails_revision()
Splits ModuleRegistry#auto_add_ports()

This takes the decoding logic, decode_input_port() and
decode_output_port(), out of auto_add_ports().
Adds Constant#__metaclass__ to add 'value' i/oport
Removes unused imports from analytics package
Removes unused imports from rpy package
Removes new_constant() function from webServices
Removes explicit inheritance in new_constant()