Cleaned up some evas_gl code and added surface cap feature.

Cleaned up some evas_gl code and added surface cap feature.
(Trying it again since this commit broke evas build yesterday.)

Previously, evas_gl_surface_create() didn't actually do
the render buffer attach to the the FBO. It was performed when
the make_current was called for the first time.  The issue
was that even though the surface was successfully created with
the given configuration, there was a possibility of make_current
failing with the error message "FBO not complete" because of
the surface configuration.

So, I've added a piece of code that checks the FBO
capabilities beforehand to set up a available surface configurations
so that it doesn't have to fail during make_current for unsupported
surface format.

Also, I've changed the surface config in a way that once the
user calls evas_gl_surface_create(), evas gl sets the config
parameter with configuration that evas_gl is actually using.

SVN revision: 70680