cylc/cylc#49: titles/descriptions in gui tooltip

This change adds titles and descriptions for tasks and
families (if available) to the hover-over information in
cylc gui. There is now hover-over functionality in the text
or tree view.
cylc/cylc#49: blank default suite/task titles

This makes the default title and description fields
blank for the suite, tasks, and families.
Merge pull request #841 from benfitzpatrick/49.task-hover-over-description

#49: add titles/descriptions to gui hover-over