Update view compilation error message

[martincostello]

After encountering dotnet/sdk#120, I noticed that the error message had not been updated to the MSBuild project system from project.json.

This PR updates the error message for the latest SDK.

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[pranavkm]

Should it say "... in the project file." instead of specifying "csproj" since views are not really not tied to the C# project system? Also, should we encourage users to use the Web.Sdk? Might not apply in your scenario, but in general it's what we'd expect most users to use and that would set this property up for you.

cc @Eilon

[martincostello]

Yeah, I wasn't exactly sure what the replacement wording should be. I'll update the PR with different text once you've got a decided alternative.

[Eilon]

@pranavkm let's discuss on Tuesday so I can understand this better.

[davidfowl]

@Eilon It's pretty simple, the error message says to turn on preserveCompilationContext in the buildOptions section of project.json. The error message needs to be updated to be msbuild project file relevant.

[pranavkm]

Spoke to @Eilon and we came up with this:

One or more compilation references are missing. Ensure that your project is referencing '{0}' and the '{1}' property is not set to false.

{0} - Microsoft.NET.Sdk.Web
{1} - PreserveCompilationContext

that get passed in.

`

[martincostello]

Cool, thank you. I will update the PR shortly.

[martincostello]

Updated in b9e5af4.

[martincostello]

@pranavkm Have updated the message as requested. Do you need me to rebase/merge from dev into this PR or not, as I think I forked it last weekend when the CI was broken.

[pranavkm]

Thanks for the update! I'll rebase it as part of merging it once Travis and AppVeyor pass.

[pranavkm]

Thanks for the PR!