Update README.md

Added instructions that will be helpful for those who want to contribute to mojito documentation.
adjusting app.json for newsboxes app
making default config.json a yaml file to add proper comments about default configurations.
supporting html5app->forceRelativePaths for yui loader, making root and base to be relative when needed.
moving logic to generate seed files into yui rs addon from deploy ac addon. making root and base for yui and app group to correlate. introducing staticHandling->serveYUIFromLocal configuration to disable serving yui from local app by default to preserve memory.
Merge branch 'develop' of github.com:yahoo/mojito into seed-refactor-html5apps
moving tests around since we moved some logic from deploy addon to rs yui addon. adjusting tests for the new schema. consolidating the scope of each new method
adding test for cache-control value
making cache-control to complain with YTS by using [public, max-age=]
adjusting comments and supporting shaker
Merge pull request #1001 from caridy/cache-control

Closes bz6110936. Fixes the Cache-Control for static assets.
adding missing requirement mojito-params-addon. trailing spaces and tabs (yes, I am a code format freak)
Merge branch 'develop' of github.com:yahoo/mojito into seed-refactor-html5apps
Merge pull request #1002 from caridy/composite-errors

adding missing requirement `mojito-params-addon` in tests
Added the property 'propagateFailure' to the mojit instance object and added a section in the composite mojit chapter about how to propagate child mojit errors to parent mojits.
Updated table for the specs object to include a table for the mojit instance object (user-defined).
Made copy edits.
Updated section on child mojits propagating errors to children with more details and with more precision.
Made a copy edit.
Merge pull request #1003 from zhouyaoji/docs_propagateFailure_property

[doc] Added documentation for the new  `propagateFailure` property that allows child mojits to propagate errors to parents.