- Split login_buttons.html and login_buttons.js into multiple files
- Specifically, make it easier to reason about the display of loginButtons whether it is in dropdown mode or not
- Split templates into subtemplates to make it easier to read the login button .html files as "tables of contents"
- Introduce Meteor._loginButtonsSession, which makes it easier to access internal session fields for loginButtons
- Unify code that calls the various Meteor.loginWithFoo() functions
Breaking change: rename "configureLoginServicesDialogForFoo" to "configureLoginServiceDialogForFoo" (in packages such as accounts-facebook)
