0.6

[natsunlee]

JobDefinition:

• New checkpointer_config section to allow configuring or replacing the default Checkpointer implementation.
• Exception will be raised if extension_directories entry is not a valid path.
• Exception will be raised if extension_directories entry is not a directory.
• Warning will be displayed if extension_directories entry is not a valid package (is a dir, but is missing init.py).
• Warning will be displayed if importing a module found in any extension_directories, including default dirs, results in an exception. The offending module will be skipped and module discovery + import will continue.

Misc:

• Changed behavior of -j and --jobdef arg to interpret path based on CWD, rather than w/ respect to the .py file where Flowmancer().start() is invoked.