readme: hard-wrap long lines at 72 chars

This makes the readme readable in a normal-sized terminal and has the
extra benefit of making diff output easier to understand on the
command line, in tools like gitg, and on GitHub.
readme: improve readability of headings
readme: copy-editing
readme: write small numbers as words
readme: simplify language about input length limits
index: reword message for IE
Merge pull request #18 from mgeisler/ie-msg

index: reword message for IE
Merge pull request #17 from mgeisler/readme-cleanups

Readme cleanups
Fixed bug: when creating a file inside an empty container the message "There are no files" is not removed
Fixed bug: visual issue in Toolbar with "Create Directory" Button and "Create File" button.
Merge pull request #19 from Leon-G/master

fixed bugs
CSS refactoring, improved styles
Merge pull request #20 from Leon-G/master

CSS refactoring, improved styles
improved style of sign out button
fixed: delete
Merge pull request #21 from Leon-G/master

fixed delete, improved style of sign out button
fixed html syntax in index.html
fixes in swift.js
liteauth Authentication Google and Facebook
Authentication: liteauth