new functionality

[hrishikeshparanjape]

Added a method called foldLeft. Using this, we can facilitate developers to use curried arguments. For example,

[1,2,3,4,5].foldLeft(0)(function(init,next){init+next});//returns 15
["a","b","c","d","e"].foldLeft("")(function(init,next){init+next});//returns "abcde"

[ollym]

@hrishikeshparanjape thanks for having a go at this. You've basically re-written the reduce method that was defined in the ECMA5 spec for javascript and is polyfixed in jstoolkit for platforms that don't support ECMA5 see here:
https://github.com/ollym/toolkit/blob/master/lib/array.js#L898-918

And so an example would be:

[1,2,3,4,5].reduce(function(sum, next) {
  sum += next;
}, 0); // returns 15

Its counterpart is reduceRight which is also polyfixed:
https://github.com/ollym/toolkit/blob/master/lib/array.js#L920-940