Replace indexOf expressions with contains

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/email/trunk@1510676 13f79535-47bb-0310-9956-ffa450edef68
Replace while loops with enhanced for loops

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/email/trunk@1510677 13f79535-47bb-0310-9956-ffa450edef68