CLDCONNECT-2131: Certification Readiness -

1. Updated POM to 3.5.2 Devkit
2. Updated LICENSE.txt and all files license headers
3. Updated Demo project
4. Updated CHANGELOG.md & USAGE.md
5. Added README.md for demo project
CLDCONNECT-2131: Update license header for demo java file
Merge pull request #7 from mulesoft/feature/CLDCONNECT-2131_Update_POM

CLDCONNECT-2131: Certification Readiness -