Tag NamedArrays v0.4.0

Mainly addressing issues raised in https://groups.google.com/d/msg/julia-users/F6wiWkbC-6I/9uP1enCa7gQJ 

 - new type definition, fully parametric in Array and Dict instance variables
 - NamedArray can contain any AbstractArray now, not just Array
 - namedArray can use any Associative now, not just Dict
 - complete rewrite of the getindex() structure, less code and more efficient
 - any type can now be used as key for the named dimensions, including any Real
 - changed the license to MIT, to be more Julia-friendly