Add properties to ScapContent class
Move hardcoded path to the Engine class.
Fix: do create policy even if there is other existing.
Introduce Scaptimony::ScapContent.store! method.
Validate DataStream file.
Make sure scap_content's certain properties are always present.
Make sure to save digest to DB

Rails use internal hash to store the properties of the object.
Make sure to have nice reporting.

Do not just return 'can't convert nil into String'
when user forget to select file for upload.
Error message for users uploading while editing.
Provide nice message when uploading file that has been already uploaded

Do not use (validates, :uniqueness => true), this will provide
more useful message.
Fix incorrect usage of change_column

Addressing:
-- change_column(:scaptimony_scap_contents, :title, {:null=>false})
rake aborted!
An error has occurred, this and all later migrations canceled:

undefined method `to_sym' for {:null=>false}:Hash
Introduce ScapContentProfile class to SCAPtimony model

An object of category (#ScapContentProfile) is any xccdf:Profile referenced
from ScapContent (XML file that can fed to SCAP scanner).
Parse xccdf:Profiles to the ScapContentProfile table.
Elaborate on the waivers feature.