Checkpoint
Almost compiling...
Compiling
Working multiple stack deployment!
Tests now compile...

...but don't pass
Fixed some tests
Fixed some tests
I believe my deserialisation approach should mean this is safe to chaneg
Deal with Stack as regards hosts properly
Allow filtering of hosts by stack
Fixup
Added test for stack filtering of data.
Move isValidForStack to Host

Thanks, @sihil
Backing out changes which should have been in another branch
Add test for resolving multiple stacks
Fix import warning
Merge pull request #156 from guardian/pw-multiple-stacks

Support for multiple stacks