first pass
add default function definition for supportsTileDataAvailable()
Don't crash if supportsTileDataAvailable is not defined.
use single function getTileDataAvailable() and add to other terrain providers
move profile scene
add SanFrancisco profile scene
jshint pass
Merge branch 'master' into tile-loading
move profiling test to sandcastle
update CHANGES.md
add specs for getTileDataAvailable()
test the getTileDataAvailable() false case as well
ammend documentation
Merge remote-tracking branch 'origin/master' into tile-loading

Conflicts:
	CHANGES.md
Add a deprecationWarning when getTileDataAvailable is not implemented.
Add note to Deprecated section.
Merge pull request #2102 from AnalyticalGraphicsInc/tile-loading

getTileDataAvailable() handling for terrain providers