Merge pull request MonoGame#531 from CartBlanche/master

Merge for 2.5.1 Release, from develop

Version 2.5.0.0 - Introduces ES 2.0 support on iOS and Android, and c…

…omes with loads of bug fixes, and we hope no major bugs!

Merge branch 'develop', remote-tracking branch 'origin' into develop

TAG 2.0.0.0 Release