[Re-implement] Add mozmaker-template options

[mmmavis]

Our current master branch is ~2700 commits behind upstream(Automattic/wp-calypso) which makes it super difficult to rebase & fix merge conflicts.

We have decided to start fresh and re-implement features that have been introduced in our fork (i.e., add mozmaker-templates options, preview feature)

More details see https://github.com/mozilla/wp-calypso/pull/40#issuecomment-212197535

• [x] add mozmaker.css and bootstrap.css to TinyMCE
• [x] remove "Testimonials" and "Portfolio" from sidebar
• [x] add mozmaker-templates so that the template options appear on sidebar

[mmmavis]

fixed in PR #42