Separates the MMP into two phases:
1). Creation of the ModelMetadata, discovery of properties and attributes
(reflection) is part of the MMP
2). Lookup of details based on attributes is now part of another phase,
and has its results cached.
Users can now implements and register an IFooMetadataProvider to customize
a single aspect of metadata (see how data annotations does it).
- #439 (2 of 3)
- correct namespaces
- correct `Resources` class and member names; add new resources
- add `RequestServices` property to `ClientModelValidationContext`
- adjust to modern `IUrlHelper` API
- add `IClientModelValidator` support in `DataAnnotationsModelValidator`
- move previously-unused `StringSplit()` to `RemoteAttribute` and rename
- rewrite `RemoteAttributeTest`
- improve test method names
Reduce number of `[Remote]` constructor overloads
- remove `AreaReference` enum and related `[Remote]` constructor overload
- use `null` or empty `string` as explicit reference to the root area
- generally reduce parameter validation; match `UrlHelper`
Cleanup
- correct Engineering Guidelines violations
- especially: add doc comments
- correct spelling error in `_additonalFieldsSplit`
nits:
- minimize `null` checks in `AdditionalFields`
- make `GetClientValidationRules` `virtual`; some subclasses use `new` today
- add tests of `DataAnnotationsModelValidator.GetClientValidationRules()`
- remove `builder.ToString()` calls since it appears
https://roslyn.codeplex.com/workitem/246 has been resolved or Moq has
worked around that issue.