`AdaptsTo` and `Supports` don't store default values correctly

When running the following code:
``` python
from traits.api import AdaptsTo, HasTraits, Instance, Interface, Supports, register_factory

class ITestInterface(Interface):
pass

class MyClass(HasTraits):
pass

class MyClassTestInterfaceAdapter(HasTraits):
object = Instance(MyClass)
def __init__(self, object):
super().__init__(self, object=object)

class MyClassTestInterfaceAdapter(HasTraits):
object = Instance(MyClass)
def __init__(self, object):
super().__init__(object=object)

register_factory(MyClassTestInterfaceAdapter, MyClass, ITestInterface)

class TestAdaptTraits(HasTraits):
supports = Supports(ITestInterface, MyClass, (), {})
adapts_to = AdaptsTo(ITestInterface, MyClass, (), {})

t = TestAdaptTraits()

print('default t.supports:', t.supports)
print('default t.supports_:', t.supports_)

t.supports = MyClass()

print('set t.supports:', t.supports)
print('set t.supports_:', t.supports_)

print('default t.adapts_to:', t.adapts_to)
print('default t.adapts_to_:', t.adapts_to_)

t.adapts_to = MyClass()

print('set t.adapts_to:', t.adapts_to)
print('set t.adapts_to_:', t.adapts_to_)
```
we get output
```
default t.supports: <__main__.MyClass object at 0x7fd61a97e620>
default t.supports_: <__main__.MyClass object at 0x7fd61a97e620>
set t.supports: <__main__.MyClassTestInterfaceAdapter object at 0x7fd61a97e6d0>
set t.supports_: <__main__.MyClass object at 0x7fd61a97e678>
default t.adapts_to: <__main__.MyClass object at 0x7fd61a97e620>
default t.adapts_to_: <__main__.MyClass object at 0x7fd61a97e620>
set t.adapts_to: <__main__.MyClass object at 0x7fd61a97e728>
set t.adapts_to_: <__main__.MyClassTestInterfaceAdapter object at 0x7fd61a97e780
```

Notice that the default values of `supports` and `adapts_to` are not of the expected types - they have not had adaptation applied to them.

This can probably be fixed by refactoring them to be simpler mapped traits.