* removeObject:inRange: was originally finding the first instance of the
  object in the range, and then doing an array-wide search-and-remove
  every time it found one. This was very clearly wrong.
* removeObject: is supposed to remove every instance of the found object.
  It wasn't doing so. Fixes microsoft#2771.
* removeObjectIdenticalTo: is supposed to remove every instance of the
  found object. It also wasn't doing so.
* removeObjectIdenticalTo:inRange: wasn't implemented.
* exchangeObjectAtIndex:withObjectAtIndex: was not using its CF
  optimized implementation.
* Methods that mutated ranges were not bounds-checking those ranges.

* Disable UIKitActionSheetTests

Causing failures in subsequent tests in the daily build.

…*.winmd, *.dll) (microsoft#2786)

Version 2017.8.25.1 was published last week, which introduces some breaking changes and requires VS2017 15.3.
For the time being, we will continue to consume 2017.4.6.1.

* Update expired app certificates

* Revert changes to Test App project files.

* Use same app certificate for each internal test app

* Fix internal app certificates

* NewCerts

* New certs

…2809)

NuGet.exe fails to restore packages. Updating to NuGet 4.4 instead
of 4.0 resolves the issue.