update burrito
fix gruntfile
v1.3.0

v1.3.0:
- add mergeObjects() to merge user settings into defaults
- change `dotsFirst` -> `dotsPrepend`
- add dotsContainer
- add default cssPrefix = 'peppermint-'
- change CSS to fulfill new prefix and the possibility of dotsContainer
being outside of `.peppermint` scope
- add disableIfOneSlide
- disable dots if there's only one slide
- update docs
- remove bonus.htm, move all tests to test/index.htm, add tests for new
features