Fix /story/add: no ajax - no encoding problems

Allow user to POST data directly to /story/add.
In handler for "get /story/add" see if we already have error or success
messages.
This faces the same problem as in 6af4e5a6ed357fcd7fa6ed0ac5edbd131171a8d6.
Add comments to make code more clear in app.js
Don't run animations on startup, so visually app starts up faster
Change placeholders in addStory.handlebars
Add link to main page to search results page when there're no results
Slightly change addStory.handlebars
Merge branch 'develop'
Bump version: 0.5.1