registration: validate username.
CoreActivity: require PIN for update prompt.
Add ViewPagerIndicator library, v2.4.1 (8cd549f).

Source: http://viewpagerindicator.com/
up
Home UI: divide tap status into several sublayouts.
Use Android app version (rather than BuildInfo) in User-Agent; remove KegbotApiImpl listener.
Remove BuildInfo.
tests: add mockito; update launch configs.