Updated Page Copy

- Updated copy according to feedback
- Removed demo engagement content since it is no longer useful
- Removed flag around engagement navbar item
Updated Graph/Chart Tooltips
Updated Metric Tooltips
Updated Engagement Table Column Ordering

Column ordering now matches that of the metrics and graph.
Updated Loading Message and Positioning
Updated Homepage Text
Removed Dead Code and Permanently Enabled Features

- The overview and performance demo pages don't even load. Time to die.
- The engagement features should always be active and therefore not behind a feature gate.
Merge pull request #103 from edx/text-updates

Text updates
Fixed Broken Acceptance Tests
Adding memcached requirement for production
Corrected Heading Usage
Hiding Non-Actionable Icons from Screen Readers
Hiding Graphs from Screen Readers
Differentiating Download CSV Text for Screen Readers
Removed Extraneous HTML Surrounding Course ID
Updated Page Structure and Added ARIA Labels
Identifying Active Navigation Items for Screen Readers
adding newrelic
Merge pull request #105 from edx/e0d/add-nr

adding newrelic
fixing typo