(CFACT-124) Refactoring block device resolver.

Refactoring the block device resolver into a base type responsible for
adding the facts and child types that are responsible for collecting
data.

This also adds the "blockdevice" structured fact representing block
device data.  Unfortunately "blockdevices" is an already existing fact
name.
(CFACT-124) Refactor SSH resolver into base type.

Refactoring the SSH resolver into a base type responsible for adding
facts and child types that are responsible for collecting SSH key data.

This also adds the ssh structured fact.