Type Agnostic Flattening

[citruspi]

This isn't necessarily ready to be merged, but I wanted to open a discussion around the handling of explicitly typed maps and slices. At the present moment, flatten will only truly flatten a string (which would be unmarshalled to a map[string]interface{}) or a variable which has been declared as a map[string]interface{} or []interface{}, which means that users who pass in an explicitly typed variable (e.g. map[string]string or []string) won't receive a completely flattened object.

e.g. see #5

The changes in this PR at the moment fix the problem for slices of strings ([]string) however there's a number of other explicit types that should theoretically be supported - booleans, numbers of various types, etc.

We could either explicitly support each of these, or simply try to catch them and copy to a []interface{}.

[jeremywohl]

Will take a look this weekend. Thanks.

[jeremywohl]

Revisiting this (long weekend! :). Still relevant? Do you have failing test cases you can supply, just to make things concrete?