performance considerations
Merge branch 'perf'

Conflicts:
	dist/es6-module-loader-sans-promises.min.js
	dist/es6-module-loader.min.js
spec bug consolidation and fixes
Merge pull request #162 from guybedford/master

Spec Update and Fixes
promises update, spec fixes, 0.7.0 prep
Delay the call to require() in system.js until needed
ie8 fixes
Merge pull request #164 from johnjbarton/delay-require-system-js

Delay the call to require() in system.js until needed
try catches in closures
Merge pull request #166 from calvinmetcalf/try-catch-opt

try catches in closures
do propogate module errors with a trace
Merge pull request #168 from ModuleLoader/err-reporting

Propogate module errors with a trace
0.7.1
update Traceur bin file links
add Reflect.global
Make System global always.
Otherwise we can't get to it in ES6
Merge pull request #170 from johnjbarton/global-system

Make System global always.