renamed 'library' to 'collection'
expose the collection an object belongs to in the setRule callback
updated the examples section of the readme

with information on the exposed 'collection' variable.
updated readme with typo & formatting fixes

for the setRule example section.
fixed a typo in the setCollection method name
Merge branch 'dependent-validation' of https://github.com/jasonbellamy/clearance into dependent-validation
bump version number to 0.2.0
updated jsdoc type for setCollection method.
Merge pull request #1 from jasonbellamy/dependent-validation

Dependent validation