0.5.6: EJS helpers, NPM 3 support and navigation improvements

• EJS helpers http://sourcejs.com/docs/spec-helpers/ #123
• Multiple tag filtering in generated navigation http://sourcejs.com/docs/data-nav/#filtering-by-tag #176
• Generated navigation templates configuration http://sourcejs.com/docs/data-nav/#customizing-templates #174
• EJS file include sandbox (security fix)
• NPM 3 support for Sourcejs as npm module #182
• Integrated anonymus tracking #141
• Updating to latest fsevents, preventing some problems with install

Planned as a last patch release before 0.6.0