Upgrade bower to most recent version.

* 'npm install' necessary
* you can delete './components' from your clone (but not './www/components'!)

Switching to default bower components dir, bower_components, but
sticking with 'www/components'.  (bower_components helps developers with
feeble memories to keep track of directory purpose, while www/components
is more for computer.)

Seems to work. Probably wishful thinking, but maybe it'll reduce travis failures...