Updated the FetchTweets_Cron class which includes minor performance improvements.

git-svn-id: https://plugins.svn.wordpress.org/fetch-tweets/trunk@894159 b8457f37-d9ea-0310-8a92-e5e31aec5664
Forgot to comment out a debug line.

git-svn-id: https://plugins.svn.wordpress.org/fetch-tweets/trunk@894161 b8457f37-d9ea-0310-8a92-e5e31aec5664