Add new methods from underscore 1.5.2.
Remove speed test from unit test suite.
Merge pull request #2830 from braddunbar/speed-test

Remove speed test from unit test suite.
Merge pull request #2829 from braddunbar/new-methods

Add new methods from underscore 1.5.2.
Add docs links for 0.9.10 to 1.1.0 to changelog
Merge pull request #2837 from akre54/docs-links

Add docs links for 0.9.10 to 1.1.0 to changelog
_addReference, to mirror _removeReference
Merge pull request #2838 from tgriesser/addReference

_addReference, to mirror _removeReference