Move to using npm for JS packages (and Bootstrap)

This involves a Makefile, used to copy the node_modules to
within the cycledash project. This commit also changes the src
of all the scripts now included with npm.

:angry: c.f. [this gem](https://www.npmjs.org/doc/misc/npm-faq.html#-node_modules-is-the-name-of-my-deity-s-arch-rival-and-a-forbidden-word-in-my-religion-can-i-configure-npm-to-use-a-different-folder-)