Integrate decent icons into the Android version

[jbphet]

For the original 0.0.1 release, I took some pieces of the header artwork and used them for the icons that are supposed to be provided. They're not horrible, but we could definitely do a lot better. @Ashton-Morris is up for creating some better versions and will get started on it, and meanwhile I'll try to figure out exactly what we need to provide both internal to the app and for the Play Store.

[jbphet]

@Ashton-Morris - For the Play Store we will need a 512px by 512px icon. More information on what Google considers to be good design can be found here:
https://developer.android.com/distribute/google-play/resources/icon-design-specifications.

I also created an initial set of icons for the app that were just an excerpt from the header artwork that you created. They look like this:

I bundled versions of this at different resolutions in the 0.1.0 version of the app, and they worked okay, but it would be good to have something more professional looking. The sizes are:

• 36 x 36
• 48 x 48
• 72 x 72
• 96 x 96
• 144 x 144

Here is the commit in which they were added so that you can see what they look like at the different sizes.

[Ashton-Morris]

I am adding these icons here.

• playstore_icon_haptics_playground_512.png
• playstore_icon_haptics_playground_144.png
• playstore_icon_haptics_playground_96.png
• playstore_icon_haptics_playground_72.png
• playstore_icon_haptics_playground_48.png
• playstore_icon_haptics_playground_36.png

[jbphet]

I've changed the graphics used by the app using the ones that @Ashton-Morris provided above. I tried to upload the 512x512 image to the app store, but apparently one also needs to add a bunch of screenshots, which I don't think is worthwhile right now. After tying this, I'm not even sure the large icon will show up anywhere if the app is never fully published, so I'm going to hold off on the large icon until later in the evolution of the app.

[Ashton-Morris]

@jbphet I looked up the circular icon and it was labeled "Existing launcher icon/ Adaptive Icon asset format (round - pixel default)"

I am not sure if we need all of those sizes so I made them at 512px. It was hard to know how much would fit in the circle so I made the slide two sizes.

playstore_icon_haptics_playground_for_circle_512.png
playstore_icon_haptics_playground_for_circle_v2_512.png