Merge pull request #1 from spderosso/master

some minor fixes in chapter + first pass on the model
Merge pull request #2 from spderosso/master

Some more cosmetic changes to the model
Merge pull request #3 from spderosso/master

Changes to the mdoel
Added postMessage and HTML tags
Merge branch 'master' of https://github.com/eskang/500lines

Conflicts:
	same-origin-policy/src/cors.als
	same-origin-policy/src/http.als
	same-origin-policy/src/main.als
	same-origin-policy/src/sop.als
Some more minor changes; new custom viz
Added stepper visualization
s/payloads/payload
misc cleanups and comment in http module
fixed extraneous space
extend comment in xmlhttpreqsop
removed extraneous socialnetwork model
s/sender/from + s/receiver/to + some s/payloads/payload  i missed