Dispose inner IAsyncEnumerators in AsyncEnumerable.SelectMany.
Do not call dispose within lock-statement.
Merge pull request #6 from Blewzman/FixAsyncEnumerableSelectMany

Dispose inner IAsyncEnumerators in AsyncEnumerable.SelectMany.
Add a Windows 8.1 + Windows Phone 8.1 Target
Add Configurations for Wpa81
Universal Unit Tests aren't A Thing yet
Add Wpa81 to BuildAll.proj