modify the f:u function #149

#149 
- f:u function
 -  Modify to the encoding process based on RFC 3986 the 'org.springframework.web.util.UriUtils#encodeQueryParam'.
- testcase
 -  Based on RFC 3986 , and added test of digit.
 -  Based on RFC 3986 , and added test of the symbol of no encoding.
 -  Based on RFC 3986 , and added test of the required Space of encoding.
 -  Based on RFC 3986 , and added test of the required symbol of encoding.