Delta's Stock Takes Off After Pilot Deal   ATLANTA (Reuters) - Shares of Delta Air Lines Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=DAL.N target=/stocks/quickinfo/fullquote"&gt;DAL.N&lt;/A&gt;  jumped on Thursday after the company and its pilots union  reached a tentative contract that will save the cash-strapped  carrier \$1 billion a year.