SEC-2192: Create DEFAULT_FILTER_NAME
Merge in AbstractSecurityWebApplicationInitializerTests.groovy
SEC-2187: Encode query parameter names and values in return_to URL
SEC-2187: Polish

Create private utf8UrlEncode method to improve readability
SEC-2191: Remove AuthenticationManagerBuilder default constructor

This ensures that users must choose what ObjectPostProcessor is being used
with AuthenticationManagerBuilder. To make things easier for users, we now
automatically add an AuthenticationManagerBuilder object that can be used
for creating an AuthenticationManager with @Autowired.