updated to new Dict syntax since [ a => b ] will be deprecated in v0.4. ...

This gets rid of deprecation warnings with recent v0.4 builds, due to new Dict syntax.

Method is to define a new macro that uses old syntax for v0.3 [ a=>b, c=>d ], and new for >=v0.4 Dict( a=>b, c=>d ). Idea is described here: https://github.com/nolta/Winston.jl/commit/9f1d9c81aa30afb68ac3dd45f65a64c718f7b293