fix(plug-in): revert conditional rebuild on change

This broke change detection for external resources included via brfs.

Instead of relying on the logic we must rely on debouncing the bundle
operation to suppress the double bundle.

The delay before an actual bundling operation is triggered may now be
configured via a browserify bundleDelay property in the karma
configuration.

Related to #69
feat(plug-in): add configure hook

This commit removes the prebundle hook to configure and adds the
prebundle event that may be used to perform additional configuration.

This allows users to reliably hook into the bundling process in
browserify@7 times.

Closes #63
chore(plug-in): document configure + add prebundle removal warning
fix(plug-in): use absolute paths to reference entry points

Closes #52
feat(integration): add config hints
fix(bro): increase default bundle delay to 700 ms
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