[AppStream] Putting review data into AppStream

[Richard Hughes]

Hey all,

I'm trying to juggle two things:

* To standardize on API for the ODRS review server so other apps can
trivially use it.
* To curate a set of verified reviews we can use offline for RHEL.

Both things could be done by returning results in AppStream format,
and with a few small tweaks we could remove a ton of JSON->C parsing
from various places. This would further cement AppStream into
relevance for other app-stores. I was thinking about something like
this as a schema:

<reviews>
  <review karma="35" date="2016-07-01" rating_percent="80">
    <summary>Looks great!</summary>
    <description><p>Long description with markup</p></description>
    <lang>en_GB</lang>
    <version>0.1.2</version>
    <display_name>Richard Hughes</display_name>
  </review>
</reviews>

Open for ideas. Thanks,

Richard.