Add support for ReSharper 8
Refactoring to better support different ReSharper versions
ReSharper detection updated to handle the new assembly name in ReSharper 8
ReSharper EditTag reflection updated to handle ReSharper 8
Rewrite ReSharperV8EditTagDetector to use ConditionalWeakTable.
This prevents keeping a (GC) reference
Fix field name
Merge pull request #1112 from oysteinkrog/resharper8_detection_fix

Add support for ReSharper 8
Cleanup the R# V8 support

- There was an inconsistency with how ReSharper was cased in type names
and namespaces. I decided to go with ReSharper.  This is how the
JetBrains team spells it on their site.
- Changed the implementation of ReSharperExternalEditAdapter a bit to
enable unit testing
- A few nit picky stile issues (mostly sealing of types)