Fix ambiguity warnings (#77)

This fixes all of the ambiguity warnings, but I can't promise that the
UniformScaling methods actually work. I had to comment out the tests
because the wrong methods are getting called due to a method sorting
bug (JuliaLang/julia#6142).
Don't define /(Number, DataArray) and /(Number, AbstractDataArray)
Add deprecation warnings

For + and - methods involving scalars, and /(Number,AbstractDataArray)
Remove deprecated tests
Add tests for copy/copy!
Merge pull request #78 from JuliaStats/sjk/ambiguity

Fix ambiguity warnings (#77)