[Docs] Status update

[naithar]

Updated implementation status for classes which status wasn't updated in PRs.
Renamed Task to Process in status. #724
Also removed all statuses for non-keyed-coding, since #626 stated that it is not supported.

URLCredential's NSCoding implementation - #708
LengthFormatter's implementation - #745
DateFormatter's .setLocalizedDateFormatFromTemplate(...) implementation - #671
NSJSONSerialization's .jsonObject(...) implementation - #54
NSAttributedString's enumerateAttributes(...) implementation - #726
FileHandle's nullDevice implementation - #690
NSDate's implementation - #620
NSProgress's implementation - #679

[broadwaylamb]

Progress seems to be implemented as well in #679.

[naithar]

@broadwaylamb seems like i missed it, thanks.

[parkera]

Thanks!