chore(build): fix watch to re-build components

[kara]

Currently the demo app does not update if the changes occur in the components (only happens if the demo app itself is updated). This PR fixes it.

[jelbourn]

LGTM

[kara]

There is probably a better/leaner way to do this, but this will at least get it working for dev. @hansl can look when he gets back, maybe?

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