feat($android): force output to PNG for Android stock #1146

Also fix unit tests in Android stock and Android Chrome.
feat($android): fix scaling tests, take 2 #1146
docs($android): Notes about scaling in Android's stock browser  #1146
[skip ci]
feat($android): Work around Android stock XHR2 & data URI bugs  #1146

Also:
- Allow chunking in non-Android-stock browsers, such as mobile Chrome
- Run file-based tests in non-Android-stock browsers
- Update documentation to reflect limitations specific to Android stock
chore($android): Feature support doc & code updates closes #1146

- Throw on addBlobs if blob uploading is not supported
- ABC ordering of supported feature flags
- New Blob upload supported flag
test(static/local/blob-maker): file-based tests just don't work reliably on any android browser #1146
chore($android): inc build after #1146