Refactor the exception code in entrypoints.py

[jimboid]

There is code and unit test duplication for the longbow() and recovery() methods. The try except blocks in the longbow and recovery methods that handle the user interrupt are identical. This code should be moved up to the launcher() scope where it will feature just once.

Doing this will require refactoring the code slightly so that the jobs structure is in the scope of launcher, it will need passing in to longbow() as part of parameters.

[jimboid]

This might not be a good idea in the end. Some library users will use the top level functions longbow() and recovery() but not the application launcher method. So it is probably better, rather than moving the exception code up to launcher() but to have a private exceptions handler method common to both longbow() and recovery() this will make testing much simpler.

[jimboid]

Completed as part of issue #61