remove node update based on enclosure node update

[anhou]

Update removing node based on @iceiilin 's PR RackHD/on-tasks#26

1. when removing a compute node, check the relationship within this node, if it's enclosed by an enclosure node, after remove compute node, also remove the relationship within enclosure node, when all nodes of an enclosure are removed, remove the enclosure automatically.
2. add nodes-api-service.js to handle nodes api function.
3. add unit tests

[tldavies]

We are testing Travis CI. Since there are no .travis.yml files it will fail.

[benbp]

I think it would be better to make the code in these promise blocks their own named functions, that way we can more easily test their functionality individually, and also have a more easily readable promise chain.

[tldavies]

test this please

[benbp]

👍

with a suggestion about some potential cleanup.

[anhou]

codes has been refactored and updated

[benbp]

This was an error that I put in a bunch of tests a while back. This statement can actually go in the before block instead of the beforeEach block, since we only need to create the sandbox once (and will save us test execution time).

[anhou]

Great. most of cases didn't pay attention on this. let's correct it from now. I've also update it

[benbp]

Thanks @anhou! Still 👍

[yyscamper]

not big problem. the better name is "removeEnclosureRelations" because it cannot be used to remove other future relations.

[yyscamper]

still 👍 , though I have some minor suggestion