Fixes a number of bugs related to charts and tables, modifies sharing feature

[jasonlally]

What it does

PR addresses one feature change

• Moves the link sharing snippet into a modal overlay (embed will live here as well when it's ready)

And several QA changes:

• Change ariaHidden -> aria-hidden
• Sets absolute offsets for charts and table
• Sets table to fill available height minus a portion for pagination (this is all just for now, table will get replaced with more robust react-virtualized in future release)
• A brute-force fix to the geometry types breaking the tables, for now display nothing, later will output as WKT, but not worrying about this until we refactor the table
• Removed some cruft from actions, reducers and initialState settings
• Added reducers to reset state for the Table, Query and Metadata when loading a new dataset

Screenshots

Share options are now in an overlay modal.