Add a compiler option to turn off "use strict" emit in modules

[dasa]

This 1.8 breaking change prevents integration with legacy libraries. See discussion at:
#3576 (comment)

[mhegazy]

new flag is --noImplicitUseStrict.

[dasa]

Thanks! This should probably be mentioned at:
https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#modules-are-now-emitted-with-a-use-strict-prologue

[mhegazy]

thanks. done.