`fdroid publish` now includes OTA ZIPs and related source

This adds support for publishing ZIP files which were built with
`fdroid build`.  This is for "Over-The-Air" (OTA) update ZIP files for
flashing to ROMs.  The first example of this is the Privileged Extension,
which must be installed by flashing an OTA ZIP on Android > 5.0.

!181
fdroid/privileged-extension#9
fdroid/privileged-extension#10
fdroid/fdroiddata!1804

Also, "if app.Binaries:" is the same as "if app.Binaries is not None:", but
is the standard Python style.
1 job for fdroid-publish-ota-zip in 15 minutes and 36 seconds (queued for 8 seconds)
Status Job ID Name Coverage
  Test
passed #8376109
test

00:15:36