Some tips from a marketer:
+Get analytics set up! I see that you've only mentioned the top of the funnel (traffic) and the bottom of the funnel (downloads). I'm assuming you don't have tracking for the full flow (traffic > install > activation > day 1-30 retention > Sales). Get this set up pronto. It's crucial to understand where the bottlenecks are and to also segment traffic to know which efforts are working.
+Marketing starts before you launch. You'll get a far stronger reaction from blogs, sites, and other people when you contact them 2-3 weeks before launch. Creates a sense of exclusivity and plus gives you some momentum to develop an installed base from Day 1. In light of this, perhaps you should call the current app an 'alpha' and re-launch to get some buzz :-)
+Major sources for you to consider: Organic: SEO Referral: Blogs, 3rd Party App Stores, Tech Sites, Forums, Quora, Stack Overflow, and where ever people who have the problem you're trying to solve is asking for help. Partner: App stores, resellers, etc... Paid: Facebook, AdWords, LinkedIn, GDN (I advise you to do thorough research before starting. It's easy to launch poorly designed campaigns and get the misinformed idea that these channels don't work) Viral: Add any social sharing anywhere you can.
+App Review sites review 100s of requests each day. I ran FreeiPadApps.net for 2-years and received 20+ app review requests/day. Mostly from indie developers, agencies, and bots. Try instead to reach out directly to an editor or writer by email/twitter/linkedin.
+SEO: Get up to best practice (title tags, headings, kw research and mapping to content), but don't bank on it. The gold rush for SEO growth circa 2007 is largely over :-(
+Look heavily into any type of 3rd party app stores for free promotion.
+Not sure of JIRA/Github has any 3rd party app pages. Worthwhile to look into this and seeing if you can get included.
With all that said, doing everything above will get you on par with what everyone else is doing. To separate yourself from the pack, the awesomeness of the product needs to take over :-)
Best of luck!