Adding basic ES6 string interpolation

[averted]

Syntax highlighting for ES6 string interpolation, adding:

javaScriptTemplateDelim - for matching delimiters ${ }
javaScriptTemplateVar - the variable part of interpolation ${...}
javaScriptTemplateString - everything between ` `

Example:

var test = "world";
var hello_world = `Hello ${test}`;