Initial commit of string interpolation plugin

First commit of the string interpolation plugin. This version has the ability to swap placeholders of the types:

 - Array
 - Boolean
 - Date
 - Number
 - Object
 - String
 - Function

Using both uppercase and lowercase place holders.
Initial commit

Updated README to reflect current functionality and usage.
Build tests

Mocha testing file for current functionality

Signed-off-by: Jon Clerck <j.m.clerck@icloud.com>