Remove the warning note about skipping, and instead show the warning when selecting skip

[christianrondeau]

When asking to run a PowerShell install script, the prompt looks like this:

Do you want to run the script?
 NOTE: If you choose not to run the script, the installation will
 fail.
 Skip is an advanced option and most likely will never be wanted.

 1) yes
 2) no [Default - Press Enter]
 3) skip

I suggest we do not show that NOTE, and instead ask for another confirmation when selecting skip (note that I'm using the #689 representation):

Do you want to run the script? (Yes/No/Skip): s
NOTE: The installation will fail. Skip is an advanced option and most likely will never be wanted.
Skip anyway? (Yes/No):

The message could probably also be improved a little bit.

For more details: https://groups.google.com/forum/#!topic/chocolatey/UVncL7PxXRg

[christianrondeau]

Moved to choco repo