These commits make MVC5 & EF6 work for me

Some Notes to the commits:
I tried to follow the guidelines as best as possible, however because most of the changes are added features there are no unit tests, because I tested them in my MVC5 application until they worked and "felt" right.

There is some testing code for the first commit however because this is a parallel testcase it is running very long so it was left out (https://gist.github.com/matthid/d9d50b309b8a037b264e), it also did not work properly on my linux box, but it is very vell possible that this was due to some resource limitations. If somebody thinks this test is worth adding then just go ahaid.

A lot of parallel/async applications which use LogicalCallContext should benefit from the first commit.

In the last commit I changed some things in the HttpApplication pipeline which "should" improve stability because we often didn't wait for asynchronous calls to finish. And I decided to not recycle HttpApplication instances when an attached module failed in an unexpected way.

"It works for me"