Add tau-checkbox-model

DESC: F
Add tau-checkbox-model doc in README

DESC: A
Add tau-checkbox-model build flow in Gruntfile

DESC: A
Change the main module name from "angular-tau-utils" to "tau-utils"

DESC: C
"angular-" seems redundant.
Release 2.0.0

DESC: RS
Merge branch 'develop' of github.com:sibevin/angular-tau-utils into develop