Detect git branch changes for compile

[Confidenceman02]

Parcel creates a cache file it uses to perform optimised builds. When using the watch strategy and switching between branches it can detect that nothing has changed cache wise because cache files are not tracked. This sometimes means builds will not reflect the latest and greatest.

There are a few ways to get around this:

• Nuke the parcel-cache directory and edit an elm file which will then produce a fresh build of all programs.
• Stop the watch strategy process and start it again.

It might be nice however to detect branch changes, or even commit changes, and do the fresh build automatically.