Extract modal widget for share
Use modal factory instead of event emitter for displaying modals
Disable pin extends hive-modal
Only element with class _cancel can trigger modal close
Send confirm overlay uses hive-modal
Disable pin uses confirm-overlay el

because flash-modal needs to be available for showing error.
Also styles disable pin modal
Rename confirm-overlay to general-purpose-overlay
Esc key dismisses modal
Merge branch 'refactor-modal'