Add (and display) pretty names in release order - not name order

[MilhouseVH]

Rather than sort the list of available builds by the displayed name, we should sort the available builds by the reverse order in which they appear in the releases.json file (ie. n, n-1, n-2, ... 0).

This PR prevents a build such as #0101 (from 2017) being listed last in the list and #1231 (from 2016) being listed first, which happens because we are sorting the list into reverse sort order based on the displayed list value - #0101 is a more recent build than #1231, and should be listed first.

In releases.json we have:

{
"0": {"file": {"sha256": "476425330acdae7227082009dbc1b13c549cfe3485b623698493c376351161b6", "name": "LibreELEC-Generic.x86_64-8.0-Milhouse-20160331012541-#0330-g46e67b7.tar", "size": "215193600"}},
"1": {"file": {"sha256": "b5c4d7f1e0a38da4a73474b5140e72dbc4f6edacec91bde65cb8883e75906d0c", "name": "LibreELEC-Generic.x86_64-8.0-Milhouse-20160331172353-#0331-gce890b1.tar", "size": "216524800"}},
...
"267": {"file": {"sha256": "7ff9274c36d8547e2565a1de127dc2656f74b0ac004da52dfe6a8615f4017ae2", "name": "LibreELEC-Generic.x86_64-8.0-Milhouse-20161231210212-#1231-g742b909.tar", "size": "214988800"}},
"268": {"file": {"sha256": "b2642309630bf7760f63c2d5e668f3b45610e60c0b5eac69d11cb380bdff9dfc", "name": "LibreELEC-Generic.x86_64-8.0-Milhouse-20170101225622-#0101-g8e3dbe5.tar", "size": "215040000"}}
}

Sorting by the key (0, 1, 267, 268 etc.) as we process the items in releases.json, and then displaying the processed items in the default order, ensures the displayed list is in the correct order regardless of what pretty name is displayed.

With this change...

Update Channel: Milhouse-8.0 (latest release: #0101):

Update Channel: LibreELEC-8.0:

Update Channel: LibreELEC-7.0:

[lrusak]

Thanks! Not sure why I didn't do this originally

[MilhouseVH]

This is the Milhouse-8.0 list without this PR (the other two channels are unchanged):

...and