Make 'await' resolve as in the C# 5.0 language specification.

This means that the awaiter type must implement INotifyCompletion and can optionally implement ICriticalNotifyCompletion.
Fixed await with generic awaiter types.
Implemented selection of best user-defined conversion operator according to §6.4.4 and §6.4.5
Test demonstrating that a const field of type decimal is not considered constant by the cecil loader.
CecilLoader: Import fields with a DecimalConstantAttribute as 'const'
When invoking a method with dynamic arguments (and there is only one applicable method), convert the result of the call to 'dynamic' (http://blogs.msdn.com/b/ericlippert/archive/2012/10/22/a-method-group-of-one.aspx)
Fixed completion bug.
[CodeAction] Fixed bug in implement interface action.
[Formatting] Fixed space within empty parentheses options.
Fixed completion bug.
[CodeCompletion] Completion engine now can generate import completion
data.
[Completion] Added missing async/await keywords.
[CodeCompletion] Added async to the type level keywords.
[CodeCompletion] Fixed variable hiding bug.
DefaultSolutionSnapshot.AddCompilation now registers the project content for GetProjectContent(string projectFileName)
Fix incorrect XmlDoc comment
Copy over some fixes from SD5.
Fix InvalidCastException in InconsistentNamingIssue.
Merge pull request #128 from erik-kallen/await-csharp5-final

Make 'await' resolve as in the C# 5.0 language specification.
Merge pull request #132 from erik-kallen/decimal-constant-bug

Decimal constant bug