Merge pull request #416 from SBoudrias/travis

Make sure npm test command don't exit with non 0
Allow custom configs to be passed to `spawn`.

The main point is to allow passing other `std` Streams to output command
content
Fix base generator tests
Simplify env#namespace and add missing tests
Rely on NPM ls for Env#lookup functionnality

Also remove a lot of noisy "too much configs" code that growed the
complexity of the code paths.

Conflicts:
	test/base.js
explore travis internals