Rename @CommandMetaData(descr) to description

In e51c428fe5ef3960f4990e1c0471d067783d4718 the metadata was
introduced using the attribute "descr".  We do not usually permit
abbreviations in APIs, and especially should not have accepted it
for an API plugins can use.

Mark descr as deprecated so current plugins can migrate.  Use
description if available, and fall back to descr for older code.

Change-Id: I662482cd228f81bf1537062b9fe03b6c23354a78
35 files changed