Removed "--check" option from "kpm build"
Working towards precompile project hook

* Introduces the idea of "aspect" assembly that can be asked for
* Roslyn compiler specifically will ask for and return
a "precompile" aspect assembly
* precompile assemblies have before/after compile hooks to
alter the "main" assembly's CSharpCompilation details
Only attempt to load preprocess aspect if project has source files
One file per type for interfaces
Pull request feedback
Bootstrapping is hard
Made some fixes to the meta programming model
- Handle propagating compilation errors to the main compilation
- Remove the check for aspect in most resolvers except for the project
- Fix the meta programming on core clr
Remove roslyn dependency from Microsoft.Framework.Runtime.Interfaces
Removed code added back in merge conflict resolution
Added meta programming sample
Actually use the dependency version when specified

Fixes #573
Check the error list as well as the build result when building
Always add an IApplicationEnvironment to the ApplicationHostContext service provider
Moved CompileModule execution
- Execute compilation modules when the compilation context is being
created. This runs within the cache context of the project itself which means
that modules can add ICacheDependencies that will get picked up by the system.
- Moved assembly neutral interface extraction to EmbeddedReferencesHelper
Implement IBeforeCompileContext on CompilationContext
Added support for new ASP.NET target frameworks
- Made it backwards compatible with k10 temporarily
- Asp.Net 50 is equivalent to .NET 4.5.3 wrt reference assemblies

#106
Added friendly name support for new platforms
- Moved all friendly name logic to FrameworkReferenceResolver
"kpm --verbose restore" prints dependency graph after a failed restore
"kpm restore" shows HTTP timings even without --verbose