2.3.0 - JAVA connector, Renderers, MarkdownIt support

• Java connector (Spring MVC) support, thanks @fabriceci #126;
• Support Markdown files side-by-side interactive editing, thanks @dereks #88;
• Custom renderers support. CodeMirror and MarkdownIt are implemented #85;
• Capability to render index file content in folder listing mode (similar to what GitHub does) #88;
• Capability to preview renderable files right after opening;
• Support Java lang in renderer / editor preview #118;
• PHP connector: added capability to define logfile path #123;
• bugfix: remove "time" query parameter upon file selection #116;
• bugfix: unable to retrieve absolute path, even when "previewUrl" is specified #116;
• bugfix: issues while copying file URL; better preview mode support #120
• bugfix: folder isn't loaded when opened from filetree and preview mode is enabled #120;
• bugfix: logger configuration doesn't take effect in PHP connector #123;
• bugfix: wrong position of "parent" item in IE #124;