Add new method(multipleReplace) in #strings

Enhanced version of replace method:
Use Case: 
>>Consider i want to replace " " with "-" and "." with "@" of the word
"Ap p.le", it would'nt be possible using replace.
>>using ${#strings.multipleReplace('Ap p.le',{' ','.'},{'-','@'})}
>> output will be "Ap-p@le"

Useful in providing href link which contains product name in URL where
in we have to replace " " and "." to "-" for SEO in web applications.
Add array, set, list version of multipleReplace method in #strings

Add array, set, list version of multipleReplace method in #strings and
performed null validation of mutlipleReplace method
Merge pull request #134 from sunil0791/2.0-master

Add new method(multipleReplace) in #strings