gulpfile: fix nodemon settings

Remove the dependency on packages, provide sensible static configuration
that works for all packages and non-packages alike.

Ignore `**/test/**` files.

Remove no longer used method `findSrc()`.

Note: as of #7, there is no `modules/package.json`, thus the previous
nodemon configuration was not picking changes made in `modules/*.js`.
Merge pull request #10 from strongloop/feature/fix-nodemon-watch

gulpfile: fix nodemon settings