Np1v8 fix

[pp-mo]

This avoids a problem exposed by netcdf saves in Iris 1.10, but which is actually due to a bug fixed by the major indexing rewrite in numpy 1.9. See : https://github.com/SciTools/iris/issues/2120

I've patched all indexing to convert tuples (where the problem was) to lists instead.

Notes:

• replaces #188, except that this converts tuples to lists instead of arrays
• converting _all_ 'vector_key' types did not work, as making arrays into lists upsets the special case of indexing with a boolean array

Checked : the Iris 1.10 tests still pass with these changes.

[pp-mo]

Stop press : I'm not sure now if this fixes the original problem...

[QuLogic]

So should #188 be re-opened or is it also still incorrect?