Close on script/module entry point

[joeyaiello]

According to #1, we're definitely starting with run.ps1 as the default entry point.

Two open questions then:

• have we already implemented entryPoint in function.json for scripts (e.g. foo.ps1)
• per the question posed in Support .psm1s via an entry point? #17, does it make sense to implement entryPoint for .psm1?

This is something we should decide we are or are not doing for the Preview milestone.

[joeyaiello]

We've decided that, for the time being, we're going to support entryPoint when you scriptFile is a .psm1, but not when it is a .ps1. We can revisit this in the future, but we currently think a shareable set of functions to be package as a module.

[daxian-dbw]

Closed via #116