function capitalizeKeys( obj ) {
	var out;
	var key;
	var k;
	if ( typeof obj !== 'object' || obj === null ) {
		throw new TypeError( format( 'invalid argument. Must provide an object. Value: `%s`.', obj ) );
	}
	out = {};
	for ( key in obj ) {
		if ( hasOwnProp( obj, key ) ) {
			if ( key === '' ) {
				out[ key ] = obj[ key ];
			} else {
				k = key.charAt( 0 ).toUpperCase() + key.slice( 1 );
				out[ k ] = obj[ key ];
			}
		}
	}
	return out;
}
Converts the first letter of each object key to uppercase.

@param {Object} obj - source object
@throws {TypeError} must provide an object
@returns {Object} new object

@example
var obj1 = {
    'aa': 1,
    'bb': 2
};

var obj2 = capitalizeKeys( obj1 );
// returns { 'Aa': 1, 'Bb': 2 }