cylc/cylc#119: add isodatetime wrapper
cylc/cylc#119: improve import prefix
cylc/cylc#119: add the LGPL isodatetime library from https://github.com/metomi/isodatetime
cylc/cylc#594: fix switch to other suite
Merge pull request #598 from benfitzpatrick/594.fix-switch-suite-gcylc

#594: fix gcylc switch to other suite
Merge pull request #597 from benfitzpatrick/119.iso-input

#119 - ISO 8601 inputs
Removed broken tests/QuickStart/a suite (addresses #581).