feat(framework): expose bundle as injected framework value

This patch returns the browserify bundle instance so other injected services
may make use of it. For example, a karma reporter may inject the browserify
framework so it can track bundle build times. Currently the framework
is `undefined` as far as the injector is concerned.
test(plug-in): add integration test runner and specs

Adds a test runner for integration testing different setups. Incorporates
integration tests into `npm test` as well. The test runner exposes the bundler
instance for testing, which relies on the change in #72. Specs added for a
simple single run, an autoWatch run where a bundled file changes, and an autoWatch run
where a non-bundled file changes.

Incorporates #72
feat(plug-in): pass basePath to browserify