Add feature to edit and synchronize blogs from local files

[ghost]

The ability to download, edit, and synchronize blogs from local files would save more time for HubSpot CMS users than any existing feature barring theme editing (which is also a huge time saver). Clicking around a web browser and interacting with WYSIWIG editors is orders of magnitude slower than using Vim, for example, to rapidly open, edit, and save files. With https://github.com/tpope/vim-unimpaired, one could rifle through hundreds of blogs using ]f whereas in the browser, the same task would be impossibly inefficient.