v0.6.0.
Fixed rollBack also for subscriptions.
Added test for subscriptions rollback.
Update Syllabus devDependency to v0.21.0.
Fixed QUIT #pop when in transaction mode, it should reset all internal status properties.
On branch master
modified:   Readme.md
modified:   lib/libra.js
modified:   package.json
new file:   test/rollback-subscription-test.js