app store and build fixes redux

[nick1udwig]

Problem

1. Core packages are not rebuilt properly when they are changed,
2. app_store does not properly return a failure for certain obvious fail cases.

Solution

1. Output the required rerun-if-changed in build.rs,
2. Handle the Responses.

Docs Update

N/A

Notes

Redo of #291

[dr-frmr]

Great, thanks, this is important