Twitter supports phrase search by quoting terms such as "Zulip API".
If we use the feature, the current twitter-bot can't detect used
search phrase. We can detect used search phrase with this change.
When invoked with search terms, twitter bot looks for these terms
in the content of a message to find out if they match. However,
Twitter can return messages that don't directly contain a search term.
This commit adds the tweeter user handle and expanded urls to the
places to look for a search term.
In order to keep all three packages (zulip, zulip_bots,
zulip_botserver) in the same repo, all package files must now
be nested one level deeper.
For instance, python-zulip-api/zulip_bots/zulip_bots/bots/, instead
of python-zulip-api/zulip_bots/bots/.
