added period directive with extensive architectural changes - eeds style fixes [axof:217]
restructured period directive and periodlist directive. Added period directives to messaging page. Messaging and grade book pages now have period info pulling in.  Fixed all period styles.[axof: 217]
Merge pull request #33 from deeger/styles

restructured period directive and periodlist directive. Added period dir...
merging latest with addComment branch att 1