Implement "Completeness Meter" pattern in My Apps

[sverzegnassi]

During the last months, we observed a huge increase of the number of available apps on OpenStore. This has been a huge challange for us, since we had to improve the set of metadata used by our search engine.

In particular, we observed that:

• A few apps do not provide a meaningful tagline
• A large part of available apps has no specified keyword
• License information is missing for some app

In order to solve this issue, and help our OpenStore uploaders to fill all the required fields, we might decide to adopt a "completeness meter" (or progress bar) in the "My Apps" section, with a few tips for improving the SEO of their entries.

Just a (random) collection of UX links (mostly first results in Google):

• https://blog.kissmetrics.com/the-progress-bar/
• http://www.creativebloq.com/ux/ui-design-pattern-tips-guiding-visitors-next-step-101413261
• http://ui-patterns.com/patterns/CompletenessMeter
• https://www.uxpin.com/studio/blog/web-form-design-best-practices-5-useful-ui-patterns-2/

[bhdouglass]

Duplicate of #58, but I'm closing the other one since this issue is much more complete.