Update README.md

Add link to Google Play Store
Merge pull request #1 from eveliotc/master

Update README.md
add donate url
Merge branch 'master' of github.com:IssacWang/Dribbo
update README
Fix build break.
resolve dependencies from maven central repository
Update support-v4 version.
Merge pull request #2 from huahang/master

Fix build break, etc.