new connector: firebase

Working: add/rm/edit
Not working yet: document create/open/del, export
reorganized demo, login, renamed firebase.js, createDocument, listDocuments
fix login for users who are not logged in
fix login for users who are not logged in
fix login for users who are logged in (?!)
Remove 'active' class form login once we're logged in
Hide login when it was successfull
Removed local-warning
fix docchooser buttons
use IDs in docchooser to identify docs, not names; firebase.getDocument
firebase.deleteDocument, .changeDocument,
connector.getFriendlyJson is now async; firebase.getFriendlyJson; export
partly fix mobile-layout, fix scrolling for small screens
More mobile fixes
Color buttons, not button texts; center button-icons
removed shadow of #bottom elements
added mobile.less to less-grunt-task
back-button, export code to sne.js, cleaned up demo.js
maineditor width in firefox
firebase.login: don't call the callback twice if we're already logged in