Better Razor Compilation Diagnostics

This pull request moves the Razor feature in ServiceStack closer to a "first class citizen". This commit improves upon #561.

**Note: Only added support for the Razor2 project.***

Also checks for `DebugMode` to prevent leaking sensitive data.

![Screen023](https://f.cloud.github.com/assets/478118/360509/867ba2a6-a198-11e2-98e8-f3d126690300.png)

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@mythz, before I continue working on this ... I'd really like to refactor the entire Razor2 project. I'm starting get a whiff of some bad code smell in the way the everything is handled in the Razor plugin.

![Screen027](https://f.cloud.github.com/assets/478118/360530/1e32d960-a19a-11e2-98cb-304d304bcc93.png)

... perhaps start a new issue where we could discuss Razor2 refactorings?