Test discovery skips over abstract base classes.

Fixes #1
Increments version to 0.1.2.
Modified nuspec to add wp8 specific output of only the PCLTesting.dll, so that PCLTesting.Portable.dll is not added to windows phone projects.
Merge github.com:davidturneruk/pcltesting
Whitespace only:

The project was a mix of tabs and spaces. I changed them all to spaces to be self-consistent and consistent with most other C# projects.
Simplified test execution code and avoids expression trees so that there's a chance this could work on iOS and to speed up test execution a bit.
Adds cancellation to test runner.
Adds missing .gitattributes file to help keep line endings consistent.
Updates to .gitignore file that adds Roslyn .ide directories.
Also simply sync's to tip of the latest recommended .gitignore file from VS/github template.
Adds output directory to .gitignore file since that's where this particular project produces build results.
Adds a bit of forced yielding to the test runner so the cancel button can actually work.
Hides the DummyType classes from Intellisense.
Adds optional progress reporting so the test running app can show a progress bar.
Fixes namespace and file location of TestRunProgress.
Adds Runner assembly as a separate entity.
Adds a view model for the runner.
Adds NuGet advertisement for wpa8.1 platform.
Adds summary text and log to view model.
The view model now takes care of displaying everything the simple app displays.
It offers run cancellation, progress, etc.
Fixes versioning on the new assembly.
Add the portable dll to the iOS platform projects so they have TestClass and TestMethod attributes.