Import ODCS Contracts

[jpraetorius]

• support basic information for info, servers, terms and servicelevels
• support for importing tables into models
• since there is no guarantee for the type that an ODCS Contract sets, we try to simply match what we can. For all other types people might specify, we use the ability of ODCS to have customProperties and allow people to specify specific mappings between 'their' types and the ones they want to have in the Datacontract by adding a magic dc_mapping_typename custom property.

Addresses #105

@jochenchrist this is at least missing tests, but before heading on to them I'd just wanted to get your opinion, since I think for ODCS the mapping is not as straight forward as for some of the other specs I've seen. We might map more things depending on more magic strings for some of the SLA Properties for example, or we could try to coerce a columns examples to strings, but I'm not sure how far we want to take this, so input is welcome, before we make this a proper PR.

[simonharrer]

Thanks! We'll start with this, and probably refine this along the way.