Corrected watch for indicatorId

Merge gone wrong - the indicatorId attribute is now observed.
Fixed bug in indicator view for empty indicatorId

The view threw an error when the indicatorId attribute was empty. Moved some
checks around to correct this problem.
Improved index.html file and updated Makefile

Added select to index.html and an extra box to test slugs. Removed copying of
index.html from Makefile as this is no longer required when using serve.js.