Fix loading language error introduced in last version

@jywsn @JoeGermuska Go ahead and push this asap
Release 0.3.5
Cleanup MapBox logo to make room for StoryMapJS logo
Merge branch 'master' of https://github.com/NUKnightLab/StoryMapJS
Add import_url parameter option
Replace history entry on successful import (prevent attempted re-import on back button)
Fix remove slide background color
Add cached storymap map in browser sessionStorage
Add clear link for slide options background color
Merge branch 'bgcolor' of github.com:NUKnightLab/StoryMapJS into bgcolor