More play info on /plays

[jrmgx]

To clean the client logic it would be nice to have at least the number of act on a given play

But it will be better to have more information like for each act, the number of scene,
and why not for each scene the number of reply so the progress would be easier to calculate

Plan

• Add the number of act on /plays
json { "act_count": 5 }
• Add a bunch of information about plays on /plays (no example in mind)

[jrmgx]

We could add author as well see #8