Unify expect_oneshot_request and expect_request

[rominf]

expect_oneshot_request and expect_request are responsible for similar actions, but expect_oneshot_request takes one optional keyword argument more (ordered). I propose to:

1. Define enum HandlerType:

class HandlerType(Enum):
    PERMANENT = 'permanent'
    ONESHOT = 'oneshot'
    ORDERED = 'ordered'

2. Make expect_request universal so that it could register permanent, oneshot, and ordered handlers by adding optional enum HandlerType argument.
3. Remove ordered argument from expect_oneshot_request.
4. Add convinience method expect_ordered_request.

[csernazs]

That's a good idea.
And the code would also be better because self.create_matcher would be called at only one place, in the expect_request method.

[csernazs]

The optional keyword argument could be type or something like that, as ordered=HandlerType.ONESHOT does not look good, as having a oneshot rule is orthogonal to whether it is ordered or not.
But this is just about the naming. :)