Analytics integration bugfixes

[michaelwalkerfl]

Few minor bugs:

• GA image/title broken
• Need to support arbitrary event names
• Need to reorganize tracking events, most ecommerce events not grouped together
• Would be nice if drop area was entire vertical space of middle pane (maybe not worth trouble)
• Dismiss changes on pop-up save bar would be nice
• Additionally, sometimes we get weird rendering: http://vrz.io/cGmG
• Sometimes save widget does not work properly (like when turning extensions on/off and then removing them)
• /static/backend/img/integrations/google-analytics-logo.png seems to be missing
• Possibly misleading referring to analytics integrations as both integrations and plugins