Remove check for getPath from master branch.

Ember.get and Ember.getPath have been unified in July of 2012.
I think that we should not check for a method that has gone 18 months ago
outside of the 0.9 branch.
Merge pull request #26 from cibernox/remove_check_for_getPath

Remove check for getPath from master branch.
Add EmberCPM.Macros.averageBy.