Fixed ObservableReleasesClient.GetAssets

to use the correct url.
Fixing some unit tests that were not doing

any assertions.
Adding Received() where it was missing.
The majority of these instances were unawaited AssertEx.Throws
They are now all either awaited or replaced with Assert.Throw
Assert.Throw was used when possible and when not an option
AssertEx.Throw was awaited.
Merge branch 'bad_assets_url' into nonfunctioning_tests
Merge branch 'master' of https://github.com/octokit/octokit.net into nonfunctioning_tests
Fixing AuthorizationsClientTests.

TheGetOrCreateApplicationAuthenticationMethod.WrapsTwoFactorFailureWi...
thTwoFactorException while I'm in here.
Removing unnecessary async/await on lambdas
Merge pull request #365 from pmacn/nonfunctioning_tests

Nonfunctioning tests