This is a fix for kubernetes-client#722

 This fixes of all tests and keeps the original API.

 It's the users responsiblility to do something the execptions
 when using `create_from_dict`, no air bag or breaks are supplied here.

We create a deployment and do the following:

```
self.assertIsNotNone(dep)
```

Which does not fail, and then the code proceeds to deletion
and fails with a 404 execption in 80% of the time, but sometimes
it works. The deployment is there, but for some reason not available for
deletion.
Travis CI also showed inconsitent behaviour on this. Python3.5 passed
but all other version failed.
With this commit we wait for the deployment to become available for
deletion and only then continue.

Using `nginx-app` deployment multiple times, is problematic because we get
conflicts or not found error.

Instead of trying to handle all cases, explicit different names
are used now. The tests now runs more reliably

This is embarrassing.

While this is a really good convention, sometimes one must import
stuff inside a try except block. This block is still at the top, but pycodestyle
treats like it isn't, because it's in an idented block, and the outeer scope.

 Renaming `yml_document` in `create_from_dict` to data. This is a bit
 clearer that this it a data item and not a string (usually document
 read from the file system).
 Also update the documentation to describe better what the functions
 `create_from_dict` and `create_from_yaml` do.

The function can create one or more Kuberenetes objects
based on the content of data. It can handle all API objects
incuding `List` type, which by itself can contain more than
one Kuberenetes API objects.

This is instead of doing this in create_from_yaml

Adding the ability to deal with strings containing yaml seems to repel
to much. So we stay with create_from_yaml with a bad name.

This removes the need fro StringIO to wrap strings.
Also note:

```
with open('foo.txt') as f:
    y = yaml.safe_load_all(f)

for i in y:
    print(i)

\# raises ValueError: I/O operation on closed file.
```

Hence, we indent the whole method body into the open block.

with open('foo.txt') as f:
    y = yaml.safe_load_all(f)
    for i in y:
        print(i)

The current PR no longer support creating from string

This follows up on the addition to create_from_yaml, the behavior is the
same.