Allow Javascript engines to be bypassed entirely.

[dustinsoftware]

If no server-side rendering will occur on a page, for instance if
component render is called with clientOnly: true, it is
pointless to initialize a Javascript engine on the server. This allows the
consumer to easily disable all server side Javascript if the server is
under heavy load.

[dustinsoftware]

I see that I forgot to sign the CLA before submitting this PR - just did that.

[Daniel15]

Seems reasonable to me!

It looks like there's a number of "invisible" changes that aren't actually related to this diff (looks like it might be changing the line endings from \r\n to \n or vice versa. Could you please revert those? We can fix those up in a separate commit :)

[Daniel15]

I can't see any noticeable change in this line so it's probably replaced newlines (\r\n with \n or vice versa). Could you please revert all the lines that aren't directly related to your change?

[dustinsoftware]

Yeah, it looks like the line endings are mixed in some of the files and VS auto corrected them :) Fix pushed

[Daniel15]

It looks like a unit test is failing. Can you please take a look? https://ci.appveyor.com/project/Daniel15/react-net/build/108

Mvc\HtmlHelperExtensionsTests.cs(39,27): error CS0854: An expression tree may not contain a call or invocation that uses optional arguments [C:\projects\react-net\src\React.Tests\React.Tests.csproj]
Mvc\HtmlHelperExtensionsTests.cs(64,27): error CS0854: An expression tree may not contain a call or invocation that uses optional arguments [C:\projects\react-net\src\React.Tests\React.Tests.csproj]
Mvc\HtmlHelperExtensionsTests.cs(86,27): error CS0854: An expression tree may not contain a call or invocation that uses optional arguments [C:\projects\react-net\src\React.Tests\React.Tests.csproj]
Done Building Project "C:\projects\react-net\src\React.Tests\React.Tests.csproj" (Rebuild target(s)) -- FAILED.

You can run the dev-build.bat file which will build the project and run the unit tests. Please ensure the bundled example site (React.Sample.Mvc4) still works fine as well.

[dustinsoftware]

Fixed, sorry about that. I had been using the sample site to test before, but forgot to build solution before I pushed.

[Daniel15]

Thanks 😄

[dustinsoftware]

@Daniel15 would you mind publishing a package update so I can consume these changes?

[Daniel15]

Will try to do that soon :) In the meantime, you could use the latest development package (see http://reactjs.net/getting-started/download.html#development-builds)

[Daniel15]

This has been included in the 2.4 release (http://reactjs.net/2016/05/2.4.0-release.html). Thanks for your contribution!