forceVBO in Mesh

At least one recent commit https://github.com/libgdx/libgdx/commit/7020231ca8b1e14995d398603de525581e3d1282 has completely disabled VBO support in the SpriteBatch class for not so clear reasons. 
My project uses GL20 for now only and I would like to use/test VBOs, so at least there's a way to bring back VBOs in spritebatch by using the forceVBO flag.
If someone could clarify why SpriteBatch was changed I would appreciate as well.
Merge pull request #346 from frustaci/patch-1

Fixed forceVBO in Mesh