Fixed issue introduced with DomCapture

[dennisroche]

In PR https://github.com/TestStack/TestStack.Seleno/pull/168, a new Castle Dynamic Proxy Interceptor was introduced to output the DOM on exception. This unfortunately broke the existing feature that captures a screenshot.This was noted by @robdmoore after https://github.com/TestStack/TestStack.Seleno/pull/168 was merged and I discovered last week when working on another contribution.

I discussed the problem with @robdmoore before starting work on this issue.

In this PR:

• I have changed the ScreenshotTest and DomCaptureTest acceptance tests to expose the issue.
• Changed the Autofac registration of the interceptors so that we create an Interceptor pipeline (http://docs.castleproject.org/Tools.DynamicProxy-Introduction.ashx). This was the main cause of the issue as the second CreateInterfaceProxyWithTarget registration for the DomCaptureProxyInterceptor replaced the CameraProxyInterceptor. Needed to use the override and create the proxy with multiple interceptors.
• Finally changed the implementation of the interceptors so that it worked correctly as part of the pipeline (down/up).

[robdmoore]

Hmm, CI auto-builds don't seem to be running. @JakeGinnivan is ci still up :P

[dennisroche]

@JakeGinnivan if you are fixing the CI servers, it would be great to get the Team City build status badge displayed on the GitHub page.

[JakeGinnivan]

CI is still up and they are building PR's.

Just looks like GitHub reporting isn't setup

[aaronpowell]

Autofac Interceptors!

¯\_(ツ)_/¯

[dennisroche]

@aaronpowell it took me a week on/off to understand how Dynamic Proxy worked. :)

[dennisroche]

I think it would be best to merge https://github.com/TestStack/TestStack.Seleno/pull/179 first as @mwhelan has also modified ScreenshotTests.cs. I don't mind rebasing.

[robdmoore]

FYI the big merge has been done so this can be fixed to be merged now.

I'm happy for @mwhelan or @MehdiK to merge it if they are happy with it. The changes look good. Thanks!