Add Angular 4 as an explicit dependency

Version bump to 1.2.1

Make placeholder optional; merge #52; bumped version

Merge branch 'SpinGo-master'

Hotfix with issue #42 fixed

Updated dependencies medium-editor and angular to latest stable versi…

…ons; clean up Gruntfile

Version bump to 0.0.6; removed deprecated library ngmin in favor of n…

…gAnnotate