update to material ui v1

[ochicf]

Closes #36.

Features:

• use @material-ui/core
• replace Accounts.ui.FormMessages instead that of the deprecated Accounts.ui.FormMessage
• implemented a simple queue for snackbar (based on Consecutive snackbars demo)
• added possibility to render social buttons with IconButton
• kept non-forcing icons policy: consumers of the package must provide their own icons

Thanks a lot @yanickrochon for your insights in the issue and for your PR in your fork, I've based this on that one.