Added prettyPrintTime and prettyPrintSize to StringUtils
Added new osgearth_seed2 app to test new caching ideas
Added osgearth_seed2 to CMakeLists
Added FindZeroMQ CMake module
Removed prettyPrintTime and prettyPrintSize from osgearth_seed.
Moved some files out of osgearth_seed2 to their own classes.
Trying to modularize the MultiProcessTileVisitor a bit more.
Added WriteTMSHandler to TileHandler
Added TaskList to TileVisitor.
Added ZMQ stuff to it's own files in the new cache app
Fix conflicts
Merge branch 'master' into topic-multiprocesssseeder

Conflicts:
	src/applications/osgearth_seed/osgearth_seed.cpp
Fix bad merge
Work on actually creating a new cache seeder that works on a whole map
Added ability to select the type of visitor in osgearth_cache2 via the command line.
You can set the concurrency and batch size in the seeder now.
Moved TileKeyListVisitor to TileVisitor in osgEarth.
Removed unused runTasks function
Exporting WriteTMSHandler
Added start of a TMS processor in osgearth_seed2
New hasData function for TileHandler
Removed test ZMQ code
Remove FindZeroMQ from main CMake
Removed unused includes