build: lowered minimum API to 16
build: lowered minimum API to 16

Blockly for Android requires a minimum of 4.1 Jellybean API 16 or we could
go lower.

Signed-off-by: Tim Harvey <84c926e4ff92d3d0f1d6317afb75d58e9d547393@gmail.com>

tharvey/BlocklyBot,tharvey/BlocklyBot