You shouldn't put new packages into the
texmf-dist tree; they'll potentially be overwritten by distribution updates. (Or more likely will just be forgotten when your upgrade to MacTeX2015 or whatever.)
Since you're on a Mac, the appropriate place to add (LaTeX) package files is
The reason why putting the file into
texmf-dist in seemingly the correct place didn't result in TeX being able to find the file is because
kpathsea, which TeX uses to find files, does not search folders dynamically for performance reasons.
The configuration file
texmf.cnf, however, makes special consideration for the "home" texmf tree linked above — since this tree will (usually) be quite small, there is little performance penalty to searching the disk when attempting to find files there.
There is also another "allocated" location to put files into your TeX distribution:
If you put files here, which will be found by all users of the computer (as opposed to the
~/Library/texmf tree), it's necessary to inform
kpathsea to update its database of files using the Terminal command: