use tw5 5.0.14-prerelease
display only configured auth servers

This is done by traversing the configuration list to create
the appropriat data for the signin.html template. Two new fields
per oauth.server server are needed 'pretty_name' and 'icon'. For
GitHub, these would be 'GitHub' and 'fa-github', respectively.

Fixes #133
Enforce suitable type on fontawesome fonts.
update tw5
add limited style to tables