Handle 'bundle' protocol in Resources.isDirectory. Fixes #3212

Within an OSGi container, URLs' protocol is "bundle://".

In order to detect if a resource is a directory, this fix
rely on the class loader's behavior, which differ between
the standalone JVM and within an OSGi environment.
Most notably, ClassLoader.getResource returns differently
when the resource's name end with a slash.

In a standard JVM, getResource doesn't care of ending slashes,
and return the URL of any existing resources. In an OSGi container
(tested with Apache Felix), ending slashe refers to a directory
(return null otherwise).

In order to test Resources.isDirectory when the protocol is "bundle://",
there are 2 options:
a) run the test within an OSGi container (using Pax Exam),
b) simulate the behavior of an OSGi class loader, which is the
implemented solution.
Update doc test source directories

The documentation tests have missed most sources
since being moved to the `working` directory.

Also update the few broken tests since this change.
Merge pull request #3414 from pvlugter/doc-tests

Update doc test source directories
Merge pull request #3406 from jlc/resources-in-osgi-bundle

Handle 'bundle' protocol in Resources.isDirectory. Fixes #3212
Make EventSource’s Enumeratee return Events instead of Strings
Fix etag format
Merge pull request #3415 from julienrf/writeable-event-source

Make EventSource’s Enumeratee return Events instead of Strings
Merge pull request #3359 from gmethvin/etag

Scala Cached Action Uses Bad ETAG
Fix etag quoting in Assets
Add QueryStringBindable for Seq
Use DigestUtils in Codecs
Merge pull request #3418 from gmethvin/binders

Add QueryStringBindable for Seq
Merge pull request #3417 from gmethvin/codecs

Use DigestUtils in Codecs
Merge pull request #3416 from gmethvin/etag

Fix etag quoting in Assets