Since
PR 572 was accepted, it would be great if you could consider the display drivers as another configuration parameter.
They're enabled in u8g_config.h by adding the respective entry to either U8G_DISPLAY_TABLE_I2C or U8G_DISPLAY_TABLE_SPI, similar like the fonts. The list of available drivers is stated as commented lines above. It's required to have the I2C and SPI drivers associated to the respective tables.
And while you're at it - there's API documentation for the u8g module by now
I'll update that once the drivers are available in master branch.
Thanks a lot for your great cloud service