Rename IdSiteModel to IdSite

[the-overengineer]

Renamed the file and class. Foundnd all references in documents and tests and updated them.

Fixes #537

[coveralls]

Coverage remained the same at 89.135% when pulling 21b0824 on feature-rename-id-sites-model into d5d09e6 on master.

[typerandom]

@Tweety-FER Thanks! Unfortunately after more investigation it looks as if the IdSiteModel is "correctly named". I.e. the resource is actually named idSiteModel. Which in my opinion is a little bit confusing, but it seems that the resource name is like that.

@robertjd Do you have any input here?

[robertjd]

Ah! I see where the confusion is here. There are two resources in the REST API:

• The ID Site Model is a view of other data that is fetched from application/:id/idSiteModel - it's not a modifiable resource.
• The ID Site is a real resource, that contains the configuration information for an ID Site. This is a real resource that can be updated (but not deleted, there one per tenant right now).

Thus, this PR has some correct changes, but some incorrect changes. The following should be true:

• Application.getIdSiteModel() should return IdSiteModel
• Organization.getIdSiteModel() should return IdSiteModel
• Tenant.getIdSites() should return IdSite

Ping @Tweety-FER for changes, thanks!