Add ui package to support blaze
Make use of UI.registerHelpers whenever possible

Use Handlebars.registerHelpers if UI isn’t defined

Update some variable names in preparation for Handlebars deprecation
Update logging to support IE
Set handlebars and ui as weak references
Use Package to get to package exports
Fix for meteor weak reference issue #1358
Merge branch 'master' of https://github.com/zimme/meteor-roles into zimme-blaze
initial work on supporting blaze & spark
only declare api.use('ui') if it is explicitly in .meteor/packages
update documentation for v1.2.7