Arbitrary resource types - base implementation

Replace hardcoded instantiation of JarResource in RepoIndex by a
loop that consults all available recognizers, similar to how the
analyzers are consulted.

Added the Default Recognizer that recognizes bundles and jars
and returns them as a Jar Resource with the appropriate mime
type. Or, otherwise returns a File Resource with mime type
unknown.

Added the Default Analayzer that tries to determine generic
identity capabilities based on filename for File Resources
(as a fallback).

Modified registration of existing (bundle) analyzers to not
consider mimetypes they can not handle.
Arbitrary resource types - added json/xml recognition

Added extension based recognition for json and xml resources to the
Default Recognizer. This could be extended to support more common
IANA media types.
Arbitrary resource types - added Metatype Recognizer

Added a recognizer for metatype files by a simple test on Resources
with mimetype xml.
Arbitrary resource types - added tests

Extended existing test suite with recognition of json & metatype
files. The former also specifies the version as part of the
filename. The latter does not.
Corrected small javadoc incorrectness

The method removes the analyzer