Add test for default attribute values
Add test for source-highlighter attribute
Add test for source-highlighter attribute
adds RubyRuntimeContext class to fix issue #93
Adds JRubyContext class for accessing JRuby from extensions and external libraries. fixes issue #93
fixes issue #96 by using JRubyRuntimeContext instead of attributes to pass JRuby Runtime to extensions
fixes issue #90 by allowing register Ruby and Java extensions from AsciidoctorJ
adds initial code for resolving issue #98
resolves issue #97 by creating ExtensionRegistry interface to be loaded as service.
resolves issue #97 by creating ExtensionRegistry interface to be loaded as service.
Add methods readDocumentStructure which read detail structure of
rendered asciidoc document for further processing on java side.

Currently it supports retrieving of id, title, style, role, attributes
and content of each block into list of individual chunks.
Merge pull request #104 from smigielski/structureddocuments

Structure documents
Merged pull request #104 manually because of conflicts.
refactor some tests and ignore one extension test because of a bug in extensions API
Fixes issue 102 by adding a method to set load paths instead of gem path.