Moves the executing property down to each blockly node
Merge pull request #45 from virtual-world-framework/branch/blockly-execute

Moves the executing property down to each blockly node
Remove versions of file that have uppercase file extensions
Add rover assets back with lowercase names and file extensions
Merge pull request #48 from virtual-world-framework/branch/fix-lowercase

Branch/fix lowercase
Add editor temporarily to facilitate debugging on the server.
Disables the run button during execution
Adds a comment to make code more clear
Merge pull request #49 from virtual-world-framework/branch/disable-run

Disables the run button during execution
Refactored the clause system so that most of the logic is in the yaml.
Moved the clause logic up into a clause manager, which exists on
the scene.
Moved some of the clauses into the scenario.  This is as much to
test the system as for any good reason, but it's not unreasonable.