Added two additional ConfigureAwait() calls.

The call missing on line 534 was causing a deadlock when run in an ASP.NET MVC4 Web API project.  Added to 586 for completeness' sake.
Merge pull request #22 from stephen-riley/master

Added two additional ConfigureAwait() calls.
Prepare for release 0.30.2
Merge branch 'master' to include 0.30.2 changes
First set of functions (First,Single,Any,Count). to be tested
adding Take, Count, LongCount, cleanup of Select