Enable livereload support for the watch task

Note that this commit does not completely set up livereload for you.
You must either use a livereload extension or manually add the
livereload script to each HTML page.
Trigger the watch task whenever */index.html is modified

This is here as a convenience for people who want to work on a swatch
with livereload. Without this, editing a .less file would trigger
livereoload, but you would still have to manually reload if you edited
the swatch's HTML preview.
Add a modified version of getSwatches() to help find swatch files
Fix a bug with isSwatchDirectory() being defined in the wrong place
Generate a list of watched files that only includes files in swatches