Basic TaskGroupSpec (single task, no config files)
Task spec instantiation with subsections.
Task spec instantiation by values lists.
Refactoring.
Give the tasks meaningful names.
Move ExternalTask to core module.
Creation of ExternalTask from task spec.
Use preferred string formatting method.

str.format is preferred over % since Python 2.6.
See <http://docs.python.org/2/library/stdtypes.html#str.format>.
Replace further % operators by str.format.

As preferred since Python 2.6.
See <http://docs.python.org/2/library/stdtypes.html#str.format>.
Allow to specify config templates.
Test creation from task spec.

No handling of template config files so far.
Handle template files on task instantiation.
Store original files.
Function to create TaskGroupSpec from file.
UI for creating tasks from spec.
Merge branch 'taskspecs'

Introducing the possibility to write 'task specs' and to use them to
launch multiple tasks at once.